Very simple question

[Paminu]

I am trying to refresh my C skills and have therefore writtin this little
program:

#include <stdio.h>

int sum (int a, int b)
{

printf(a+b);
return a+b;
}


int main()
{
sum(1,2);

}

But when I compile I get :

test.c: In function `sum':
test.c:5: warning: passing arg 1 of `printf' makes pointer from integer
without a cast

me@ubuntu:~/opgaver$ ./test
Segmentation fault


What am I missing?

 

[Richard Heathfield]

Paminu said:

I am trying to refresh my C skills and have therefore writtin this little
program:

#include <stdio.h>

int sum (int a, int b)
{

printf(a+b);

printf("The sum is %d\n", a + b);

 

[Christopher Benson-Manica]

In addition to Mr. Heathfield's comments...

int main()

int main( void ) /* better */

{
sum(1,2);

return 0; /* return is required in C89 */

 

[Randy Howard]

Paminu wrote

I am trying to refresh my C skills and have therefore writtin this little
program:

#include <stdio.h>

int sum (int a, int b)
{

printf(a+b);

$ man 3 printf

<or look it up in whatever documentation is appropriate for your
compiler and library configuration>

 

[Mike Wahler]

I am trying to refresh my C skills and have therefore writtin this little
program:

#include <stdio.h>

int sum (int a, int b)
{

printf(a+b);
return a+b;
}


int main()
{
sum(1,2);

}

But when I compile I get :

test.c: In function `sum':
test.c:5: warning: passing arg 1 of `printf' makes pointer from integer
without a cast

me@ubuntu:~/opgaver$ ./test
Segmentation fault


What am I missing?

You forgot to read the documentation for 'printf()' or
a textbook which explains how to use it.

printf("%d\n", a + b);

"Style" note: Your function is named 'sum()'. So that's what it
should do. Nothing else. Output doesn't belong in it. It limits
the function's usability. What if I want to call 'sum()' several
times as part of other computation, and only want output of the
final result?

#include <stdio.h>

int sum(int a, int b)
{
return a + b;
}

int main(void)
{
int i = 5;
int j = sum(i, 3); /* your way would give unwanted output here */
printf("%d\n", sum(j, 2));
return 0;
}

-Mike