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H.5 Calling Procedures Written in Other Languages |
SheerPower can call procedures written in other programming languages as long as
they are contained in a DLL as a global routine. An example of this is
calling routines in the Microsoft provided msvcrt.dll library.
The call statement is used to call and execute library routines. These
routines can perform procedures so the developer does not have to write the
code from scratch.
Routines within a DLL are called using the call statement, followed by a quoted string which contains the name of the routine to be called:
Some routines take arguments. By default, most arguments are passed by their value. Strings and arrays are always passed by reference. If you want to explicitly pass an argument by reference (the pointer to the argument), use the by ref option:
Note:
When calling a routine, you must enclose its name in quotes.
For example:
The library to which the routine belongs must have been specified in a
library statement."strlen"(). This ensures the routine's
upper and lower case formatting is preserved.
Routines within a DLL are called using the call statement, followed by a quoted string which contains the name of the routine to be called:
Some routines take arguments. By default, most arguments are passed by their value. Strings and arrays are always passed by reference. If you want to explicitly pass an argument by reference (the pointer to the argument), use the by ref option:
myvar% = 45
call "my_routine" (myvar% by ref, myarray%() by ref)
When a routine is called, it may also return a value. The variable
_integer will hold this value if the routine returns an integer.
If the routine returns a pointer to a null-terminated character string
(char*), you can call the routine with the prefix
char*. After the routine completes, _string will
contain a copy of the returned string.
For example:
myvar% = 45
call "char* my_routine" (myvar% by ref, myarray%() by ref)
print 'Returned string was: '; _string
This demonstrates how _string automatically holds the returned string
when the routine is called with the char* prefix.
msvcrt.dll library and
calls the strlen and _getcwd functions/routines.
library 'msvcrt.dll'
text$ = 'Hello there!'
call 'strlen' (text$)
print 'The length of text$ is: '; _integer
call 'char* _getcwd'()
print 'The current working directory is: '; _string
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