Example Program: (Demo function declaration) --- This is the C++ Square function definition: click here ; This is the C++ MAIN function definition: click here ; Compile with: CC C-subroutine2a.C C-subroutine2b.C. Experiment: try "lying" to the compiler: change the declaration of "Square"

For example, use the following statement to include the stdio.h file: #include <stdio.h> You do not need to do anything special to use subroutines from the Standard C library ( libc.a ).

Same example using TMS320C30. Note that in the C-language, the main( ) program and a subroutine( ) are basically structured in the same way. In fact, the main( ) program really is a subroutine (called from the operating system?). The discussion below can be extended to the main( ) program itself. CALLING SUBROUTINES

I am attempting to compile and link a Fortran code calling c subroutine: Fortran code: program adder integer a,b a=1 b=2 call addnums(a,b) stop end program C code: void addnums( int* a, int* b ) { int c = (*a) + (*b); /* convert pointers to values, then add them */ printf("sum of %i and %i is %i\n", (*a), (*b), c ); }

For example, a subroutine may sort numbers in an integer array or perform a complex mathematical operation on an input variable (e.g., calculate sin(x)). It should be noted, that the block of instructions that constitute a subroutine can be included at every point in the main program when that task is needed.

In the example below I am using M98 to call a subroutine. This is how Mach3 software operates. It uses the same rules as a subprogram call but you have the choice of putting it in the subroutine folder or after the M30. cnc subprogram G code example % OMILL-RECTANGLE WITH ARCS G17 G20 G40 G49 G80 G90 T1 M06 G00 G54 X-2.6 Y-.25 S2000 M03 G43 H1 Z1.