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Introduction
BaCon
usage and parameters
General
syntax
Mathematics,
variables
Arrays
Associative
arrays
Declaration
Relations,
lookups
Basic logic
programming
Strings by value or by
reference
Execute BaCon source
program using a 'shebang'
Creating
and linking to libraries created with BaCon
Step
1: create a library
Step 2:
compile the library
Step 3: copy
library to a system path
Step 4:
update linker cache
Step 5:
demonstration program
Step 6:
compile and link
Statements
and functions
Appendix A: Runtime
error codes
BaCon is an acronym for BAsic CONverter. The BaCon BASIC converter is a tool to convert programs written in BASIC syntax to C. The resulting C program should be compilable with GCC or CC.
BaCon is intended to be a programming aid in creating small tools which can be compiled on different Unix-based platforms. It tries to revive the days of the good old BASIC.
The BaCon converter passes expressions and numeric assignments to the C compiler without verification or modification. This means that the assignment symbol '=', which is used in C programs, also must be used in BaCon programs. Another consequence is that the C comparison symbol '==' also must be used in BaCon (there are aliases for the comparison symbol like 'EQ' or 'IS').
Therefore BaCon can be considered a lazy converter: it relies on the expression parser of the C compiler.
To use BaCon, download the converter and make sure the program has executable rights. There is no difference between the Kornshell version or the BASH version. Only one of them is needed. Suppose the BASH version is downloaded, the converter can be used as follows:
bash ./bacon.bash myprog.bac
By default the converter will refer to '/bin/bash' by itself. It uses a so-called 'shebang' which allows the program to run standalone provided the executable rights are set correctly. This way there is no need to execute BaCon with an explicit use of BASH. So this is valid:
./bacon.bash myprog.bac
All BaCon programs should use the '.bac' extension. But it is not necessary to provide this extension for conversion. So BaCon also understands the following syntax:
./bacon.bash myprog
The BaCon Basic Converter can be started with the following parameters.
-c: determine which C compiler should create the binary. The default value is 'gcc'. Example: ./bacon -c cc prog. In this situation, the converted program will be compiled by a C compiler called 'cc'.
-l: pass libraries to the C linker
-o: pass compiler options to the C compiler
-i: the compilation will use an additional external C include file
-d: determine the directory where BaCon should store the generated C files. Default value is the current directory.
-f: create a shared object of the program
-n: do not compile the C code automatically after conversion.
-j: invoke C preprocessor to interpret C macros which were added to BaCon source code.
-p: do not cleanup the generated C files. Default behavior is to delete all generated C files automatically.
-b: use bacon in the 'shebang' so BaCon programs can be executed similar to a script (binary version of BaCon only).
-v: shows the current version of BaCon.
-h: shows an overview of all possible options on the prompt. Same as the '-?' parameter.
So how to pass compiler and linker flags to the C compiler? Here are a few examples.
Convert and compile program with debug symbols: ./bacon -o “-g” yourprogram.bac
Convert and compile program and export functions as symbols: ./bacon -o “-export-dynamic” yourprogram.bac
Convert and compile program using TCC and export functions as symbols: ./bacon -c tcc -o “-rdynamic” yourprogram.bac
Convert and compile program forcing 32bit and optimize for platform: ./bacon -o “-m32 -mtune=native” yourprogram.bac
Convert and compile program linking to a particular library: ./bacon -l somelib yourprogram.bac
BaCon consists of statements, functions and expressions. Each line should begin with a statement. A line may continue onto the next line by using the '\' symbol at the end. The LET statement may be omitted, so a line may contain an assignment. Functions always return a value or string. Functions created in the program can be used standalone. Expressions are not converted but are passed unchanged to the C compiler (lazy conversion).
BaCon does not need line numbers. One statement per line is accepted. If there are more statements on the same line then an error occurs.
All keywords must be written in capitals. Keywords in small letters are considered to be variables. Statements are always written without using brackets. Only functions must use brackets to enclose their arguments.
Variables will be declared implicitly from the first moment a variable is used. If a variable name ends with the '$' symbol, a string variable is assumed. Otherwise it is considered to be numeric. By default, BaCon assumes long type with NUMBER variables. With the 'DECLARE' statement it is possible to define a variable to any other C-type explicitly.
The three main types in BaCon are defined as STRING, NUMBER and FLOATING. These are translated to char*, long and double.
Subroutines may be defined using SUB/ENDSUB and do not return a value. With the FUNCTON/ENDFUNCTION statements a routine can be defined which does return a value. The return value must be explicitly stated with the statement RETURN.
Variables which are used and declared within a SUB or FUNCTION by default have a global scope, meaning that they are seen by the main program and other routines. With the LOCAL statement variables can be declared local to the FUNCTION or SUB.
The standard operators for mathematics can be used, like '+' for addition, '-' for substraction, '/' for division and '*' for multiplication. For the binary 'and', the '&' symbol must be used, and for the binary 'or' use the pipe symbol '|'. Binary shifts are possible with '>>' and '<<'. The C operators '+=', '-=' and the like are not valid in BaCon.
Variable names may be of any length but cannot start with a number or an underscore symbol.
An array will never be declared implicitly by BaCon, so arrays must be declared explicitly. This can be done by using the keyword GLOBAL for arrays which should be globally visible, or LOCAL for local array variables.
Arrays must be declared in the C syntax, using square brackets for each dimension. For example, a local string array must be declared like this: 'LOCAL array$[5]'. Two-dimensional arrays are written like 'array[5][5]', three-dimensional arrays like 'array[5][5][5]' and so on.
By default, if an array is declared as 'array[5]', then it means that the array elements range from 0 to 4. Element 5 is not part of the array. This behavior can be changed using the OPTION BASE statement. If OPTION BASE is set to 1, the mentioned 'array[5]' will have a range from 1 to 5.
Arrays must be declared with fixed dimensions, meaning that it is not possible to determine the dimensions of an array using variables or functions, so during program runtime. The reason for this is that the C compiler needs to know the array dimensions during compile time. Therefore the dimensions of an array must be defined with fixed numbers or with CONST definitions.
In BaCon, numeric arrays can have all dimensions, but string arrays cannot have more than one dimension.
An associative array is an array of which the index is determined by a string, instead of a number. Associative arrays use round brackets '(…)' instead of the square brackets '[…]' used by normal arrays.
An associative array can use any kind of string for the index, and it can have an unlimited amount of elements. The declaration of associative arrays therefore never mentions the range. An associative array always has one dimension. Also note that the OPTION BASE statement has no impact.
To declare an associative array, the following syntax applies: DECLARE info ASSOC int. This declares an array containing integer values. To assign a value, using a random string “abcd” as example: info(“abcd”) = 1. Similarly an associative array containing other types can be declared, for example strings: DECLARE txt$ ASSOC STRING. An associative array cannot be declared using the LOCAL keyword.
For the index, it is also possible to use the STR$ function to convert numbers or numerical variables to strings: PRINT txt$(STR$(123)).
In BaCon it is possible to setup relations between associative arrays of the same type. This may be convenient when multiple arrays with the same index need to be set at once. To setup a relation the RELATE keyword can be used, e.g.: RELATE assoc TO other. Now for each index in the array 'assoc', the same index in the array 'other' is set.
Next to this the actual elements in an associative array can be looked up using the LOOKUP statement. This statement returns an array containing all indexes. The size of the array is dynamically declared as it depends on the amount of available elements.
With the current associative array commands it is possible to perform basic logic programming. Consider the following Logic program which can be executed with any Prolog implementation:
mortal(X)
:-
human(X).
human(socrates).
human(sappho).
human(august).
mortals_are:
write('Mortals
are:'),
mortal(X),
write(X),
fail.
The following BaCon program does the same thing:
DECLARE
human, mortal ASSOC int
RELATE human TO mortal
human("socrates")
= TRUE
human("sappho") = TRUE
human("august")
= TRUE
PRINT "Mortals are:"
LOOKUP mortal TO
member$ SIZE amount
FOR x = 0 TO amount - 1
PRINT
member$(x)
NEXT
Strings can be stored by value or by reference. By value means that a copy of the original string is stored in a variable. This happens automatically when when a string variablename ends with the '$' symbol.
Sometimes it may be necessary to refer to a string by reference. In such a case, simply declare a variable name as STRING but omit the '$' at the end. Such a variable will point to the same memory location as the original string. The following examples should show the difference between by value and by reference.
When using string variables by value:
a$
= "I am here"
b$ = a$
a$ = "Hello
world..."
PRINT a$, b$
This will print “Hello world...I am here”. The variables point to their own memory area so they contain different strings. Now consider the following code:
a$
= "Hello world..."
LOCAL b TYPE STRING
b = a$
a$ =
"Goodbye..."
PRINT a$, b FORMAT "%s%s\n"
This will print “Goodbye...Goodbye...” because the variable 'b' points to the same memory area as 'a$'. (The optional FORMAT forces the variable 'b' to be printed as a string, otherwise BaCon assumes that the variable 'b' contains a value.)
In Unix, it is possible to execute a script directly from the commandline. The first line of the script must describe the interpreter. This is called a 'shebang'. A similar thing can be done with BaCon. If the first line of the BaCon program contains a shebang, the program will be compiled automatically. If the shebang also adds the '-b' option, the program will be compiled and also executed, as if it were a script. For example:
#!/dir/to/bacon -b
a$
= "Run from shebang"
PRINT a$
The first line points to the BaCon binary using the '-b' option. Also make sure to set the executable rights of the BaCon source program. Now the program can be executed like any other script. So if the program is called 'shebang.bac', then from the Unix commandline just run the following to compile and execute it:
./shebang.bac
Note that this way of executing a BaCon source program only can be performed with the binary version of BaCon.
With Bacon, it is possible to create libraries. In the world of Unix these are known as shared objects. The following steps should be sufficient to create and link to BaCon libraries.
The below program only contains a function, which accepts one argument and returns a value.
FUNCTION
bla (NUMBER n)
LOCAL i
i = 5 * n
RETURN i
END
FUNCTION
In this example the program will be saved as 'libdemo.bac'. Note that the name must begin with the prefix 'lib'. This is a Unix convention. The linker will search for library names starting with these three letters.
The program must be compiled using the '-f' flag: bacon -f libdemo.bac
This will create a file called 'libdemo.so'.
To use the library, it must be located in a place which is known to the linker. There are more ways to achieve this. For sake of simplicity, in this example the library will be copied to a system location. It is common usage to copy additional libraries to '/usr/local/lib': sudo cp libdemo.so /usr/local/lib
The linker now must become aware that there is a new library. Update the linker cache with the following command: sudo ldconfig
The following program uses the function from the new library:
PROTO
bla
x = 5
result = bla(x)
PRINT result
This program first declares the function 'bla' as prototype, so the BaCon parser will not choke on this external function. Then the external function is invoked and the result is printed on the screen.
Now the program must be compiled with reference to the library created before. This can be done as follows: ./bacon -l “-ldemo” program.bac
With the Unix command 'ldd' it will be visible that the resulting binary indeed has a dependency with the new library!
When executed, the result of this program should show 25.
ABS(x)
Type: function
Returns the absolute value of x.
ADDRESS(x)
Type: function
Returns the memory address of a variable or function. The ADDRESS function can be used when passing pointers to imported C functions (see IMPORT).
ALARM <sub>, <time>
Type: statement
Sets a SUB to be executed in <time> seconds. This will interrupt any action the BaCon currently is performing; an alarm always has priority. Example:
SUB
dinner
PRINT "Dinner time!"
END SUB
ALARM
dinner, 5
ALIAS <function> TO <alias>
Type: statement
Defines an alias to an existing function or an imported function. Aliases cannot be created for statements or operators. Example:
ALIAS
"DEC" TO "ConvertToDecimal"
PRINT
ConvertToDecimal("AB1E")
x AND y
Type: operator
Performs a logical 'and' between x and y. For the binary 'and', use the '&' symbol.
ARGUMENT$
Type: variable
Reserved variable containing name of the program and the arguments to the program. These are all separated by spaces.
ASC(char)
Type: function
Calculates the ASCII value of char (opposite of CHR$). Example:
PRINT ASC("x")
CALL <sub name> [TO <var>]
Type: statement
Calls a subroutine if the sub is defined at the end of the program. With the optional TO also a function can be invoked which stores the result value in <var>. Example:
CALL
fh2cel(72) TO celsius
PRINT celsius
CATCH GOTO <label> | RESET
Type: statement
Sets the error function where the program should jump to if error checking is enabled with TRAP. For an example, see the RESUME statement. Using the RESET argument restores the BaCon default error messages.
CHANGEDIR <directory>
Type: statement
Changes the current working directory. Example:
CHANGEDIR "/tmp/mydir"
CHOP$(x)
Type: function
Returns a string where on both sides <CR>, <NL>, <TAB> and <SPACE> have been removed.
CHR$(x)
Type: function
Returns the character belonging to ASCII number x. This function does the opposite of ASC. The value for x must lay between 0 and 255.
CLEAR
Type: statement
Clears the terminal screen. To be used with ANSI compliant terminals.
CLOSE FILE|DIRECTORY|NETWORK|MEMORY <handle>
Type: statement
Close file, directory or network identified by handle. Example:
CLOSE FILE myfile
COLOR
<BG|FG> TO
<BLACK|RED|GREEN|YELLOW|BLUE|MAGENTA|CYAN|WHITE>
COLOR
<NORMAL|INTENSE|INVERSE|RESET>
Type: statement
Sets coloring for the output of characters in a terminal screen. For FG, the foreground color is set. With BG, the background color is set. This only works with ANSI compliant terminals. Example:
COLOR
FG TO GREEN
PRINT "This is green!"
COLOR RESET
COLUMNS
Type: function
Returns the amount of columns in the current ANSI compliant terminal.
CONCAT$(x$, y$, …)
Type: function
Returns the concatenation of x$, y$, ... The CONCAT function can accept an unlimited amount of arguments. Example:
PRINT CONCAT$("Help this is ", name$, " carrying a strange ", thing$)
CONST <var> = <value> | <expr>
Type: statement
Assigns a value a to a label which cannot be changed during execution of the program. Consts are globally visible from the point where they are defined. Example:
CONST
WinSize = 100
CONST Screen = WinSize * 10 + 5
COPY <file> TO <newfile>
Type: statement
Copies a file to a new file. Example:
COPY "file.txt" TO "/tmp/new.txt"
COS(x)
Type: function
Returns the calculated COSINUS of x.
CURDIR$
Type: function
Returns the full path of the current working directory.
CURSOR <ON|OFF>
Type: statement
Shows or hides the cursor in the current ANSI compliant terminal.
DATA <x, y, z....>
Type: statement
Defines float, integer or string data. The DATA statement always is globally visible. In a DATA statement there can only be one type of data. The data can be read with the READ statement. If more data is read than available, then in case of numeric data a '0' will be retrieved, and in case of string data an empty string. Example:
DATA
1, 2, 3, 4, 5, 6
DATA 0.5, 0.7,0.11, 0.15
DATA "one",
"two", "three", "four"
DAY(x)
Type: function
Returns the day of the month (1-31) where x is amount of seconds since January 1, 1970. Example:
PRINT DAY(NOW)
DEC(x)
Type: function
Calculates the decimal value of x, where x should be passed as a string. Example:
PRINT DEC("AB1E")
DECLARE <var>[,var2,var3,...] TYPE|ASSOC <c-type>
Type: statement
Explicitely declares a variable to a C-type. The ASSOC keyword is used to declare associative arrays. This is always a global declaration. Use LOCAL for local declarations. This function is available for compatibility reasons. It does the same thing as the GLOBAL statement.
Optionally, within a SUB or FUNCTION it is possible to use DECLARE in combination with RECORD to define a record variable which is visible globally.
DECR <x>[, y]
Type: statement
Decreases variable <x> with 1. Optionally, the variable <x> can be decreased by <y>. Example:
x
= 10
DECR x
PRINT x
DECR x, 3
PRINT x
DEF FN <label> [(args)] = <value> | <expr>
Type: statement
Assigns a value or expression to a label. Example:
DEF
FN func(x) = 3 * x
PRINT func(12)
DELETE <FILE|DIRECTORY> <name>
Type: statement
Deletes a file or directory. If an error occurs then this can be retrieved with the CATCH statement. Example:
DELETE FILE "/tmp/data.txt"
END [value]
Type: statement
Exits a program. Optionally, a value can be provided which the program can return to the shell.
ENDFILE(filehandle)
Type: function
Function to check if EOF on a file opened with <handle> is reached. If the end of a file is reached, the value '1' is returned, else this function returns '0'. For an example, see the OPEN statement.
x EQ y
Type: operator
Verifies if x is equal to y. This is an alias for the C construct '=='. To improve readability it is also possible to use IS instead. Example:
IF
q EQ 5 THEN
PRINT "q equals 5"
END IF
EQUAL(x$, y$)
Type: function
Returns 1 if x$ and y$ are equal, or 0 if x$ and y$ are not equal. This is the only way in BaCon to compare two strings. Use OPTION COMPARE to establish case insensitive conversion. Example:
IF
EQUAL(a$, "Hello") THEN
PRINT "world"
END
IF
ERR$(x)
Type: function
Returns the runtime error as a human readable string, identified by x. Example:
PRINT ERR$(ERROR)
ERROR
Type: variable
This is a reserved variable, which contains the last error number. This variable may be reset during runtime.
EVEN(x)
Type: function
Returns 1 if x is even, else returns 0.
EXEC$(command$)
Type: function
Executes an operating system command and returns the result to the BaCon program. See SYSTEM to plainly execute a system command. Example:
result$ = EXEC$("ls -l")
FALSE
Type: variable
Represents and returns the value of '0'.
FILEEXISTS(filename)
Type: function
Verifies if <filename> exists. If the file exists, this function returns 1, else it returns 0.
FILELEN(filename)
Type: function
Returns the size of a file identified by <filename>. If an error occurs this function returns '-1'. The ERR$ statement can be used to find out the error if TRAP is set to LOCAL. Example:
length = FILELEN("/etc/passwd")
FILETYPE(filename)
Type: function
Returns the type of a file identified by <filename>. If an error occurs this function returns '0'. The ERR$ statement can be used find out which error if TRAP is set to LOCAL. The following values may be returned:
|
Value |
Meaning |
|---|---|
|
1 |
Regular file |
|
2 |
Directory |
|
3 |
Character device |
|
4 |
Block device |
|
5 |
Named pipe (FIFO) |
|
6 |
Symbolic link |
|
7 |
Socket |
FILL$(x, y)
Type: function
Returns an x amount of ASCII character y. The value for y must lay between 0 and 255. Example printing 10 times the character '@':
PRINT FILL$(10, 64)
FLOOR(x)
Type: function
Returns the rounded down value of x.
FOR
var = x TO y [STEP z]
<body>
[BREAK]
NEXT
[var]
Type: statement
With FOR/NEXT a body of statements can be repeated a fixed amount of times. The variable will be increased with 1 unless a STEP is specified. Example:
FOR
x = 1 TO 10 STEP 0.5
PRINT x
NEXT
FREE x
Type: statement
Releases claimed memory (see also MEMORY).
FUNCTION
<name> ()|(STRING s, NUMBER i, FLOATING
f)
<body>
RETURN <x>
ENDFUNCTION
| END FUNCTION
Type: statement
Defines a function. The variables within a function are visible globally, unless declared with the LOCAL statement. A FUNCTION always returns a value, this should explicitly be specified with the RETURN statement. Instead of the Bacon types STRING, NUMBER and FLOATING for the incoming arguments, also regular C-types can be used. Example:
FUNCTION
fh2cel (NUMBER fahrenheit)
LOCAL celsius
celsius =
fahrenheit*9/5 + 32
RETURN celsius
END FUNCTION
GETBYTE <memory> FROM <filehandle> [SIZE x]
Type: statement
Retrieves binary data into a memory area from a file identified by handle, with optional size of x bytes (default size = 1 byte). This command is useful in case binary data must be fetched. Example:
OPEN
prog$ FOR READING AS myfile
txt = MEMORY(100)
GETBYTE
txt FROM myfile SIZE 100
CLOSE FILE myfile
GETENVIRON$(var$)
Type: function
Returns the value of the environment variable 'var$'. If the environment variable does not exist, this function returns an empty string. See SETENVIRON to set an environment variable.
GETFILE <var> FROM <dirhandle>
Type: statement
Reads a file from an opened directory. Subsequent reads return the files in the directory. If there are no more files then an empty string is returned. Refer to the OPEN statement for an example on usage.
GETKEY
Type: function
Returns a key from the keyboard without waiting for <RETURN>-key. Example:
PRINT
"Press <escape> to exit now..."
key = GETKEY
IF
key EQ 27 THEN
END
END IF
GETLINE <var> FROM <handle>
Type: statement
Reads a line of data from a memory area identified by <handle> into a variable. The memory area can be opened in streaming mode using the the OPEN statement. A line of text is read until the next newline character. Example:
GETLINE txt$ FROM mymemory
See also PUTLINE to store lines of text into memory areas.
GETX
GETY
Type: function
Returns the current x and y position of the cursor. An ANSI compliant terminal is required. See GOTOXY to set the cursor position.
GLOBAL <var>[,var2,var3,...] TYPE|ASSOC <c-type>
Type: statement
Defines a global variable <var> with C type <type>. The ASSOC keyword is used to declare associative arrays. In most cases BaCon tries to declare variables implicitly, so in most cases there is no need to use this statement. Variables declared with the GLOBAL keyword are visible in each part of the program. See also the LOCAL keyword for local declarations. Example:
GLOBAL x TYPE float
GOTO <label>
Type: statement
Jumps to a label defined elsewhere in the program. See also the LABEL statement.
GOTOXY x, y
Type: statement
Puts cursor to position x,y where 0,0 is the upper left of the terminal screen. An ANSI compliant terminal is required. Example:
CLEAR
FOR x = 5 TO 10
GOTOXY x, x
PRINT "Hello
world"
NEXT
GOTOXY 1, 12
HEX$(x)
Type: function
Calculates the hexadecimal value of x. Returns a string with the result.
HOUR(x)
Type: function
Returns the hour (0-23) where x is the amount of seconds since January 1, 1970.
IF
<expression>
THEN
<body>
[ELIF]
<body>
[ELSE]
[body]
ENDIF
| END IF
Type: statement
Execute <body> if <expression> is true. If <expression> is not true then run the optional ELSE body. Multiple IF's can be written with ELIF. The IF construction should end with ENDIF or END IF. Example:
a
= 0
IF a > 10 THEN
PRINT "This is
strange:"
PRINT "a is bigger than 10"
ELSE
PRINT
"a is smaller than 10"
END IF
If only one function or statement has to be executed, then the if-statement also can be used without a body. For example:
IF
age > 18 THEN PRINT "You are an adult"
ELSE INPUT
"Your age: ", age
IMPORT <function[(type arg1, type arg2, ...)]> FROM <library> TYPE <type> [ALIAS word]
Type: statement
Import a function from a C library defining the type of returnvalue. Optionally, the type of arguments can be specified. Also optionally it is possible to define an alias under which the imported function will be known to BaCon. Examples:
IMPORT
"ioctl" FROM "libc.so" TYPE int
IMPORT
"gdk_draw_line(long, long, int, int, int, int)" FROM
"libgdk-x11-2.0.so" TYPE void
IMPORT "atan(double)"
FROM "libm.so" TYPE double ALIAS "arctangens"
INCLUDE <filename>
Type: statement
Adds a external BaCon file to current program. Nested includes are not supported. Example:
INCLUDE "beep.bac"
INCR <x>[, y]
Type: statement
Increases variable <x> with 1. Optionally, the variable <x> may be increased by <y>.
INPUT [text[, ... ,]<variable[$]>
Type: statement
Gets input from the user. If the variable ends with a '$' then the input is considered to be a string. Otherwise it will be treated as numeric. Example:
INPUT
a$
PRINT "You entered the following: ", a$
The input-statement also can print text. The input variable always must be present at the end of the line. Example:
INPUT
"What is your age? ", age
PRINT "You probably were
born in ", YEAR(NOW) - age
INSTR(haystack$, needle$ [,z])
Type: function
Returns the position where needle$ begins in haystack$, optionally starting at position z. If not found then this function returns the value '0'.
INSTRREV(haystack$, needle$ [,z])
Type: function
Returns the position where needle$ begins in haystack$, but start searching from the end of haystack$, optionally at position z also counting from the end. If not found then this function returns the value '0'.
ISFALSE(x)
Type: function
Verifies if x is equal to 0.
ISTRUE(x)
Type: function
Verifies if x is not equal to 0.
LABEL <label>
Type: statement
Defines a label which can be jumped to with a GOTO statement. A label may not contain spaces.
LCASE$(x$)
Type: function
Converts x$ to lowercase characters and returns the result. Example:
PRINT LCASE$("ThIs Is All LoWeRcAsE")
LEFT$(x$, y)
Type: function
Returns y characters from the left of x$.
LEN(x$)
Type: function
Returns the length of x$.
LET <var> = <value> | <expr>
Type: statement
Assigns a value or result from an expression to a variable. The LET stament may be omitted. Example:
LET a = 10
LOCAL <var>[,var2,var3,...] [TYPE <c-type>]
Type: statement
This statement only has sense within functions, subroutines or records. It defines a local variable <var> with C type <type> which will not be visible for other functions, subroutines or records, nor for the main program. If the TYPE keyword is omitted then variables are assumed to be of 'long' type. If TYPE is omitted and the variablename ends with a '$' then the variable will be a string. Example:
LOCAL
x, y TYPE int
LOCAL q$
LOOKUP <assoc> TO <array> SIZE <variable>
Type: statement
Retrieves all indexnames created in an associative array. The results are stored in <array>. As it sometimes is unknown how many elements this resulting array will contain, the array should not be declared explicitly. Instead, LOOKUP will declare the result array dynamically.
If LOOKUP is being used in a function or sub, then <array> will have a local scope. Else <array> will be visible globally, and can be accessed within all functions and subs.
The total amount of elements created in this array is stored in <variable>. This variable can be declared explicitly using LOCAL or GLOBAL. Example:
LOOKUP
mortal TO men$ SIZE amount
FOR x = 0 TO amount – 1
PRINT
men$[x]
NEXT
MAKEDIR <directory>
Type: statement
Creates and empty directory. Parent directories are created implicitly. Errors like write permissions, disk quota issues and so on can be retrieved with CATCH. Example:
MAKEDIR "/tmp/mydir/is/here"
MAXRANDOM
Type: variable
Reserved variable which contains the maximum value RND can generate. The actual value may vary on different operating systems.
MEMORY(x)
Type: function
Claims memory of x byte size, returning the address where the memory block resides. Use FREE to release the memory again.
MEMREWIND <handle>
Type: statement
Returns to the beginning of a memory area opened with <handle>.
MEMTELL(handle)
Type: function
Returns the current position in the memory area opened with <handle>.
MID$(x$, y, [z])
Type: function
Returns z characters starting at position y in x$. The parameter 'z' is optional. When omitted, this function returns everything from position 'y' until the end of the string.
MINUTE(x)
Type: function
Returns the minute (0-59) where x is amount of seconds since January 1, 1970.
MOD(x, y)
Type: function
Returns the modulo of x divided by y.
MONTH(x)
Type: function
Returns the month (1-12) in a year, where x is the amount of seconds since January 1, 1970.
MONTH$(x)
Type: function
Returns the month of the year as string in the system's locale ("January", "February", etc), where x is the amount of seconds since January 1, 1970.
x NE y
Type: operator
Checks if x and y are not equal. This is an alias for the C construct '!='. Instead, ISNOT can be used as well to improve code readability.
NL$
Type: variable
Represents the newline as a string.
NOT(x)
Type: function
Returns the negation of x.
NOW
Type: function
Returns the amount of seconds since January 1, 1970.
ODD(x)
Type: Function
Returns 1 if x is odd, else returns 0.
OPEN <file|dir|address> FOR READING|WRITING|APPENDING|READWRITE|DIRECTORY|NETWORK|SERVER|MEMORY AS <handle>
Type: statement
When used with READING, WRITING, APPENDING or READWRITE, this statement opens a file assigning a handle to it. The READING keyword opens a file for read-only, the WRITING for writing, APPENDING to append data and READWRITE opens a file both for reading and writing. Example:
OPEN
"data.txt" FOR READING AS myfile
WHILE
NOT(ENDFILE(myfile)) DO
READLN txt$ FROM myfile
IF
NOT(ENDFILE(myfile)) THEN
PRINT txt$
ENDIF
WEND
CLOSE
FILE myfile
When used with DIRECTORY a directory is opened as a stream. Subsequent reads will return the files in the directory. Example:
OPEN
"." FOR DIRECTORY AS mydir
REPEAT
GETFILE myfile$
FROM mydir
PRINT "File found: ", myfile$
UNTIL
ISFALSE(LEN(myfile$))
CLOSE DIRECTORY mydir
When used with NETWORK a network address is opened as a stream.
OPEN
"www.google.com:80" FOR NETWORK AS mynet
SEND "GET
/ HTTP/1.1\r\nHost: www.google.com\r\n\r\n" TO
mynet
REPEAT
RECEIVE dat$ FROM mynet
total$ =
CONCAT$(total$, dat$)
UNTIL ISFALSE(WAIT(mynet, 500))
PRINT
total$
CLOSE NETWORK mynet
When used with SERVER the program starts as a server to accept incoming TCP connections.
OPEN
"localhost:51000" FOR SERVER AS myserver
WHILE
NOT(EQUAL(LEFT$(dat$, 4), "quit")) DO
RECEIVE dat$
FROM myserver
PRINT "Found: ", dat$
WEND
CLOSE
SERVER myserver
When used with MEMORY a memory area can be used in streaming mode.
data
= MEMORY(500)
OPEN data FOR MEMORY AS mem
PUTLINE "Hello
cruel world" TO mem
MEMREWIND mem
GETLINE txt$ FROM
mem
CLOSE MEMORY mem
PRINT txt$
OPTION <BASE x> | <COMPARE x> | <SOCKET x>
Type: statement
Sets an option to define the behavior of the compiled BaCon program. It is recommended to use this statement in the beginning of the program, to avoid unexpected results.
The BASE argument determines the lower bound of arrays. By default the lower bound is set to 0. Note that this setting also has impact on the array returned by the SPLIT statement.
The COMPARE argument defines if string comparisons with EQUAL should be case sensitive (0) or not (1). The default is case sensitive comparison (0).
The SOCKET argument defines the timeout for setting up a socket to an IP address. Default value is 5 seconds.
x OR y
Type: operator
Performs a logical or between x and y. For the binary or, use the '|' symbol.
OS$
Type: function
Function which returns the name and machine of the current Operating System.
PEEK(x)
Type: function
Returns a 1-byte value stored at memory address x.
PI
Type: variable
Reserved variable containing the number for PI: 3.14159265.
POKE <x>, <y>
Type: statement
Stores a 1-byte value <y> at memory addres <x>. Use PEEK to retrieve a value from a memory address. Example:
mem
= MEMORY(500)
POKE mem, 32
POW(x, y)
Type: function
Raise x to the power of y.
PRINT [value] | [text] | [variable] | [expression] [FORMAT <format>] | [,] | [;]
Type: statement
Prints a numeric value, text, variable or result from expression. A semicolon at the end of the line prevents printing a newline. Example:
PRINT
"This line does ";
PRINT "end here: ";
PRINT
linenr + 2
Multiple arguments maybe used but they must be separated with a comma. Examples:
PRINT
"This is operating system: ", OS$
PRINT "Sum of 1
and 2 is: ", 1 + 2
The FORMAT argument is optional and can be used to specify different types in the PRINT argument. The syntax of FORMAT is similar to the printf argument in C. Example:
PRINT "My age is ", 40, " years which is ", 10 + 30 FORMAT "%s%d%s%d\n"
PROTO <function name>[,function name [, ...]] [ALIAS word]
Type: statement
Defines an external function so it is accepted by the BaCon parser. Mutliple function names may be mentioned but these should be separated by a comma. Optionally, PROTO accepts an alias which can be used instead of the original function name. During compilation the BaCon program must explicitly be linked with an external library to resolve the function name. Examples:
PROTO
glClear, glClearColor, glEnable
PROTO "glutSolidTeapot"
ALIAS "TeaPot"
PULL x
Type: statement
Puts a value from the internal stack into variable <x>. The argument must be a variable. The stack will decrease to the next available value.
If the internal stack has reached its last value, subsequent PULL's will retrieve this last value. If no value has been pushed before, a PULL will deliver 0 for numeric values and an empty string for string values.
PUSH <x>|<expression>
Type: statement
Pushes a value <x> or expression to the internal stack. There is no limit to the amount of values which can be put onto the stack other than the available memory. The principle of the stack is Last In, First Out.
See also PULL to get a value from the stack.
PUTBYTE <memory> TO <filehandle> [SIZE x]
Type: statement
Store binary data from a memory area to a file identified by handle with optional size of x bytes (default size = 1 byte). This is the inverse of GETBYTE, refer to this command for an example.
PUTLINE "text"|<var> TO <handle>
Type: statement
Write a line of data to a memory area identified by handle. The line will be terminated by a newline character. The memory area must be set in streaming mode first using OPEN. Example:
PUTLINE "hello world" TO mymemory
RANDOM (x)
Type: function
This is a convenience function to generate a random integer number between 0 and x - 1. See also RND for more flexibility in creating random numbers. Example creating a random number between 1 and 100:
number = RANDOM(100) + 1
READ <x[$]>
Type: statement
Reads a value from a DATA block into variable <x>. Example:
LOCAL
dat[8]
FOR i = 0 TO 7
READ dat[i]
NEXT
DATA 10, 20,
30, 40, 50, 60, 70, 80
READLN <var> FROM <handle>
Type: statement
Reads a line of data from a file identified by handle into a variable. Example:
READLN txt$ FROM myfile
RECEIVE <var> FROM <handle> [SIZE chunk]
Type: statement
Reads data from a network location identified by handle into a variable. Subsequent reads return more data until the network buffer is empty. The chunk size can be determined with the optional SIZE argument. Example:
OPEN
"www.google.com:80" FOR NETWORK AS mynet
SEND "GET
/ HTTP/1.1\r\nHost: www.google.com\r\n\r\n" TO
mynet
REPEAT
RECEIVE dat$ FROM mynet
total$ =
CONCAT$(total$, dat$)
UNTIL ISFALSE(WAIT(mynet, 500))
CLOSE
NETWORK mynet
RECORD
<var>
LOCAL <member1> TYPE
<type>
LOCAL <member2> TYPE
<type>
....
END RECORD
Type: statement
Defines a record <var> with members. If the record is defined in the mainprogram, it automatically will be globally visible. If the record is defined within a function, the record will have a local scope, meaning that it is only visible within that function. To declare a global record in a function, use the DECLARE or GLOBAL keyword.
The members of a record should be defined using the LOCAL statement and can be accessed with the 'var.member' notation. Also refer to WITH for assigning values to multiple members at the same time. Example:
RECORD
var
LOCAL x
LOCAL y
END RECORD
var.x = 10
var.y
= 20
PRINT var.x + var.y
REGEX (txt$, expr$)
Type: function
Applies a POSIX Extended Regular Expression expr$ to the string txt$. If the expression matches, the value '1' is returned. Else this function returns '0'. Examples:
'
Does the string match alfanum character
PRINT REGEX("Hello
world", "[[:alnum:]]")
'
Does the string *not* match a number
PRINT REGEX("Hello
world", "[^0-9]")
'
Does the string contain an a, l or z
PRINT REGEX("Hello
world", "a|l|z")
RELATE <assocA> TO <assocB>[, assocC, ...]
Type: statement
This statement creates a relation between associative arrays. Effectively this will result into duplication of settings; an index in array <assocA> also will be set in array <assocB>. A previous declaration of the associative arrays involved is required. Example:
DECLARE
human, mortal ASSOC int
RELATE human TO mortal
human("socrates")
= TRUE
PRINT mortal("socrates")
REM [remark]
Type: statement
Adds a comment to your code. Any type of string may follow the REM statement. Instead of REM also the single quote symbol ' maybe used to insert comments in the code.
RENAME <filename> TO <new filename>
Type: statement
Renames a file. If different paths are included the file is moved from one path to the other. Example:
RENAME "tmp.txt" TO "real.txt"
REPEAT
<body>
[BREAK]
UNTIL
<expr>
Type: statement
The REPEAT/UNTIL construction repeats a body of statements. The difference with WHILE/WEND is that the body will be executed at least once. The optional BREAK statement can be used to break out the loop. Example:
REPEAT
C
= GETKEY
UNTIL C EQ 27
REPLACE$(haystack$, needle$, replacement$)
Type: function
Substitutes a substring <needle$> in <haystack$> with <replacement$> and returns the result. The replacement does not necessarily need to be of the same size as the substring. Example:
PRINT
REPLACE$("Hello world", "l", "p")
PRINT
REPLACE$("Some text", "me", "123")
RESIZE <x>, <y>
Type: statement
Resizes memory area starting at address <x> to an amount of <y> bytes. If the area enlarged, the original contents of the area remain intact.
RESTORE
Type: statement
Restores the internal DATA pointer(s) to the beginning of the first DATA statement.
RESUME
Type: function
When an error is catched, this statement tries to continue after the statement where an error occurred. Example:
TRAP
LOCAL
CATCH GOTO print_err
DELETE FILE "somefile.txt"
PRINT
"Resumed..."
END
LABEL print_err
PRINT
ERR$(ERROR)
RESUME
REVERSE$(x$)
Type: function
Returns the reverse of x$.
REWIND <handle>
Type: statement
Returns to the beginning of a file opened with <handle>.
RIGHT$(x$, y)
Type: function
Returns y characters from the right of x$.
RND
Type: function
Returns a random number between 0 and the reserved variable MAXRANDOM. The generation of random numbers can be seeded with the statement SEED. Example:
SEED
NOW
x = RND
ROUND(x)
Type: function
Rounds x to the nearest integer number. For compatibility reasons, also the keyword INT may be used instead.
ROWS
Type: function
Returns the amount of rows in the current ANSI compliant terminal.
SEARCH(handle, string)
Type: function
Searches for a <string> in file opened with <handle>. Returns the offset in the file where the first occurrence of <string> is located. Use SEEK to effectively put the filepointer at this position. If the string is not found, then the value '-1' is returned.
SECOND(x)
Type: function
Returns the second (0-59) where x is the amount of seconds since January 1, 1970.
SEED x
Type: statement
Seeds the random number generator with some value. After that, subsequent usages of RND will return numbers in a random order. Note that seeding the random number generator with the same number also will result in the same sequence of random numbers.
By default, a BaCon program will automatically seed the random number generator with the current time as soon as it is executed, so it may not be needed to use this function explicitly. Example:
SEED NOW
SEEK <handle> OFFSET <offset> [WHENCE START|CURRENT|END]
Type: statement
Puts the filepointer to new position at <offset>, optionally starting from <whence>.
SELECT <variable> CASE <body>[;] [DEFAULT <body>] END SELECT
Type: statement
With this statement a variable can be examined on multiple values. Optionally, if none of the values match the SELECT statement may fall back to the DEFAULT clause. Example:
SELECT
myvar
CASE 1
PRINT "Value is 1"
CASE
5
PRINT "Value is 5"
CASE
2*3
PRINT "Value is ",
2*3
DEFAULT
PRINT "Value not found"
END
SELECT
Contrary to most implementations, in BaCon the CASE keyword also may refer to expressions and variables. Also BaCon knows how to 'fall through' using a semicolon, in case multiple values lead to the same result:
SELECT
st$
CASE "Man"
PRINT "It's
male"
CASE "Woman"
PRINT "It's
female"
CASE "Child";
CASE
"Animal"
PRINT "It's
it"
DEFAULT
PRINT "Value not found"
END
SELECT
SEND <var> TO <handle>
Type: statement
Sends data to a network location identified by handle. For an example, see the RECEIVE statement.
SETENVIRON var$, value$
Type: statement
Sets the environment variable 'var$' to 'value$'. If the environment variable already exists, this statement will overwrite a previous value. See GETENVIRON$ to retrieve the value of an environment variable. Example:
SETENVIRON "LANG", "C"
SIN(x)
Type: function
Returns the calculated SINUS of x
SLEEP <x>
Type: statement
Sleeps <x> milliseconds (sleep 1000 is 1 second).
SORT <x> [DOWN]
Type: statement
Sorts the one-dimensional array <x> in ascending order. Only the basename of the array should be mentioned, not the dimension. The array may both be a numeric or a string array. Optionally the keyword DOWN can be used to sort in descending order. Example:
GLOBAL
a$[5] TYPE STRING
a$[0] = "Hello"
a$[1] = "my”
a$[2]
= "good"
a$[4] = "friend"
SORT a$
SPC$(x)
Type: function
Returns an x amount of spaces.
SPLIT <string> BY <sub> TO <array> SIZE <variable>
Type: statement
This statement can split a string into smaller pieces. The <sub> argument determines where the string is being splitted. The results are stored in <array>. As it cannot be known in advance how many elements this resulting array will contain, the array may not be declared before with LOCAL or GLOBAL.
If SPLIT is being used in a function or sub, then <array> will have a local scope. Else <array> will be visible globally, and can be accessed within all functions and subs.
The total amount of elements created in this array is stored in <variable>. This variable can be declared explicitly using LOCAL or GLOBAL. Example usage:
OPTION
BASE 1
LOCAL dimension
SPLIT "one two three" BY "
" TO array$ SIZE dimension
FOR i = 1 TO dimension
PRINT
array$[i]
NEXT
SQR(x)
Type: function
Calculates the square root from a number.
STOP
Type: statement
Halts the current program and returns to the Unix prompt. The program can be resumed by performing the Unix command 'fg', or by sending the CONT signal to its pid: kill -CONT <pid>.
STR$(x)
Type: function
Convert numeric value x to a string (opposite of VAL). Example:
PRINT STR$(123)
SUB
<name>[(STRING s, NUMBER i, FLOATING f)]
<body>
ENDSUB
| END SUB
Type: statement
Defines a subprocedure. A subprocedure never returns a value (use FUNCTION instead).
Variables used in a sub are visible globally, unless declared with LOCAL. The incoming arguments are always local. Instead of the BaCon types STRING, NUMBER and FLOATING for the incoming arguments, also regular C-types also can be used. Example:
SUB
add(NUMBER x, NUMBER y)
LOCAL result
PRINT "The
sum of x and y is: ";
result = x + y
PRINT
result
END SUB
SYSTEM <command$>
Type: statement
Executes an operating system command. Use EXEC$ to catch the result of an operating system command. Example:
SYSTEM "ls -l"
TAB$(x)
Type: function
Returns an x amount of tabs.
TAN(x)
Type: function
Returns the calculated tangens of x.
TELL(handle)
Type: function
Returns current position in file opened with <handle>.
TIMEVALUE(a,b,c,d,e,f)
Type: function
Returns the amount of seconds since January 1 1970, from year (a), month (b), day (c), hour (d), minute (e), and seconds (f). Example:
PRINT TIMEVALUE(2009, 11, 29, 12, 0, 0)
TRACE <ON|OFF>
Type: statement
Starts trace mode. The program will wait for a key to continue. After each keypress, the next line of source code is printed to the screen, and then executed. Pressing the ESCAPE key will exit the program.
TRAP <LOCAL|SYSTEM>
Type: statement
Sets the runtime error trapping. By default, trapping is performed by the operating system. This means that if an error occurs, a signal will be catched by the program and a generic error message is displayed on the prompt. The program will then exit gracefully. If trapping is put to LOCAL, BaCon tries to examine statements and functions where possible, and will display an error message based on the operating system internals, indicating which statement or function causes a problem. Optionally, when a CATCH is set, BaCon can jump to a LABEL instead, where a self-defined error function can be executed, and from where a RESUME is possible. Note that the CATCH statement does not work with functions.
The setting LOCAL decreases the performance of the program, because additional runtime checks are carried out when the program is executed.
TRUE
Type: variable
Represents and returns the value of '1'. This is the opposite of the FALSE variable.
UCASE$(x$)
Type: function
Converts x$ to uppercase characters and returns the result. See LCASE$ to do the opposite.
USEC
<body>
ENDUSEC
| END USEC
Type: statement
Defines a body with C code. This code is passed unmodified to the C compiler. Example:
USEC
char
*str;
str = strdup("Hello");
printf("%s\n",
str);
END USEC
VAL(x$)
Type: function
Returns the actual value of x$. This is the opposite of STR$. Example:
nr$
= "456"
q = VAL(nr$)
VERSION$
Type: variable
Reserved variable which contains the BaCon version number.
WAIT(handle, milliseconds)
Type: function
Suspends the program for a maximum of <milliseconds> until data becomes available on <handle>.
This is especially useful in network programs where a RECEIVE will block if there is no data available. The WAIT function checks the handle and if there is data in the queue, it returns with value '1'. If there is no data then it waits for at most <milliseconds> before it returns. If there is no data available, WAIT returns '0'. Refer to the RECEIVE statement for an example.
WEEK(x)
Type: function
Returns the week number (1-53) in a year, where x is the amount of seconds since January 1, 1970. Example:
PRINT WEEK(NOW)
WEEKDAY$(x)
Type: function
Returns the day of the week as a string in the system's locale ("Monday", "Tuesday", etc), where x is the amount of seconds since January 1, 1970.
WHILE <expr>
[DO]
<body>
[BREAK]
WEND
Type: statement
The WHILE/WEND is used to repeat a body of statements and functions. The DO keyword is optional. The optional BREAK statement can be used to break out the loop. Example:
LET
a = 5
WHILE a > 0 DO
PRINT a
a = a - 1
WEND
WITH
<var>
.<var> = <value>
.<var> =
<value>
....
END WITH
Type: statement
Assign values to individual members of a RECORD. For example:
WITH
myrecord
.name$ = "Peter"
.age =
40
.street = Westlands 1
.city = The Hague
END WITH
WRITELN "text"|<var> TO <handle>
Type: statement
Write a line of data to a file identified by handle. Example:
WRITELN "hello world" TO myfile
YEAR(x)
Type: function
Returns the year where x is amount of seconds since January 1, 1970. Example:
PRINT YEAR(NOW)
|
Code |
Meaning |
|---|---|
|
0 |
Success |
|
1 |
Trying to access illegal memory |
|
2 |
Error opening file |
|
3 |
Could not open library |
|
4 |
Symbol not found in library |
|
5 |
Wrong hexvalue |
|
6 |
Unable to claim memory |
|
7 |
Unable to delete file |
|
8 |
Could not open directory |
|
9 |
Unable to rename file |
|
10 |
NETWORK argument should contain colon with port number |
|
11 |
Could not resolve hostname |
|
12 |
Socket error |
|
13 |
Unable to open address |
|
14 |
Error reading from socket |
|
15 |
Error sending to socket |
|
16 |
Error checking socket |
|
17 |
Unable to bind the specified socket address |
|
18 |
Unable to listen to socket address |
|
19 |
Cannot accept incoming connection |
|
20 |
Unable to remove directory |
|
21 |
Unable to create directory |
|
22 |
Unable to change to directory |
|
23 |
GETENVIRON argument does not exist as environment variable |
|
24 |
Unable to stat file |
|
25 |
Search contains illegal string |
|
26 |
Cannot return OS name |
|
27 |
Illegal regex expression |
|
28 |
Unable to create bidirectional pipes |
|
29 |
Unable to fork process |
|
30 |
Cannot read from pipe |
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