C programming - use of functions

[manutdateroma]

Hi, ive just started computing and programming in C at uni as a freshmen. I was wondering if someone could explain what is a function and how it works and how it cud be used?

[Reisswolf]

Sorry, this question is just too broad to give a meaningful answer. If you narrow it down, you will get better responses.

Surely you can find out what is a function by looking at any number of books and web articles and tutorials on C programming. Programming in C is one such source; you can find many others simply by typing "c programming" into Google.

If there is a particular C function, such as shmget--or even an aspect of C functions, such as function pointers--that is giving you trouble, we can help. Otherwise the question invites the kind of pontification that is neither instructive for the questioner nor satisfying for the respondent.

[manutdateroma]

What i meant is how people create their own function or subprogram eg:

int function(int swap1, int swap2);
int main (int argv, int **argc){
int a;
int b;
{some code}
function(a,b)

return(0);
}

int function(int swap1, int swap2){
{some code}
return(function)
}

get the basic idea what im asking?

[Reisswolf]

Are you looking to swap two integers? Here are a couple of functions that would do it.

#include <stdio.h>

/* Declarations */
void swap_with_temp (int*, int*);
void swap_wo_temp (int*, int*);





int main (int argc, char *argv[]) {

	int x = 5, y = 10;

	swap_with_temp (&x, &y);
	printf ("%d\t%d\n", x, y); /* x is now 10, y is now 5 */

	swap_wo_temp (&x, &y);
	printf ("%d\t%d\n", x, y); /* x is now 5, y is now 10 */

	return 0;

} /* End main () */





void swap_with_temp (int *a, int *b) {

	int temp = *a;
	*a = *b;
	*b = temp;

} /* End swap_with_temp() */





void swap_wo_temp (int *a, int *b) {

	*a = *a + *b;
	*b = *a - *b;
	*a = *a - *b;

} /* End swap_wo_temp () */

I hope this helps.