C Program Structure - C Functions

Syntax:

filename.h:

return_type function_name2( type arg1, type arg2, ... );

extern type variable2; /*external declaration*/

External declaration

filename.c:

#include <filename2.h>

#include "filename.h"

type variable1;

type variable2;

return_type function_name1( type arg1, type arg2, ... );

main( )

{

    :

    return 0;

}

return_type function_name1( type arg1, type arg2, ... )

{

    :

    return expression;

}

return_type function_name2( type arg1, type arg2, ... )

{

    :

    return expression;

}

Module variables definitions

Local function prototype

Main function - start running here.

Module function

Example:

my_module.h:

typedef enum days {

    sunday,

    monday,

    tusday

} T_DAY;

#define NUM 100

extern T_DAY x[NUM];

/* Module's interface functions -

    to be called from other modules */

void Set_X();

void Get_X();

my_module.c:

#include <stdio.h>

#include "my_module.h"

T_DAY x[NUM];

int n;

char c;

int Calc_X();

void Set_X()

{

   ...

}

void Get_X()

{

   ...

}

int Calc_X()

{

   ...

}

main.c:

#include <stdio.h>

#include "my_module.h"

main()

{

    int x;

    Set_X();

    x = Get_X();

    printf("x value=%d", x);

    return 0;

}