Programming Forums > Application Development > C

colt · Apr 26th, 2005, 8:55 AM

Hi, I am having a big little problem to return to the main function, the value of a sum operation. As you can see in the code, all I want to do is to return the data contained in the 'res' variable (n1 + n2) to the main function.

There I call the function SUM through a call function "SUM (int res); "
to display in the end of the main function, the result of the sum: n1 + n2, but I get the following errors:

test.c: In function `main':
test.c:15: error: syntax error before "int"

So what I am doing wrong? What I need to do to sucessfully be able to return the data contained in the res variable to the main function to finally see the result of the mathematical operation?

Thanks in advance.

[code]#include <stdio.h>

int SUM (int n1, int n2);

main ()
{
int n1, n2, i;

while (5 == 5) {
printf ("To close the program, type 0: ");
scanf ("%d", &i);
if (i == 0) break;
printf ("Type the numbers that should be used to do the sum: ");
scanf ("%d %d", &n1, &n2);
SUM (int res);
}
}

int SUM (int n1, int n2)
{
int res;
res = n1 + n2;
printf ("The result is: %d", res);
return res;
}

Eggbert · Apr 26th, 2005, 9:34 AM

>while (5 == 5) {
This is strange. Not only that you used <constant> == <constant>, but because you chose 5 as the constant. A more conventional way to create an infinite while loop is

(Toggle Plain Text)

while ( 1 ) {
  /* Body */
}

>SUM (int res);
A function call does not declare parameters, it takes arguments:

(Toggle Plain Text)

SUM (n1, n2);

Here is the same program with the necessary fixes:

(Toggle Plain Text)

#include <stdio.h>

int SUM (int n1, int n2);

int main ()
{
  int n1, n2, i;

  while (1) {
    printf ("To close the program, type 0: ");
    scanf ("%d", &i);
    if (i == 0) break;
    printf ("Type the numbers that should be used to do the sum: ");
    scanf ("%d %d", &n1, &n2);
    SUM (n1, n2);
  }
}

int SUM (int n1, int n2)
{
  int res;
  res = n1 + n2;
  printf ("The result is: %d", res);
  return res;
}

mackenga · Apr 28th, 2005, 8:11 AM

Nice solution. I just thought I'd add; another conventional way to do an infinite loop is for (;;), which arguably is even clearer since it doesn't even have the 'dummy condition' constant 1.

Infinite Recursion · Apr 28th, 2005, 8:56 AM

Speaking of infinite loops... here's the "cool" way...

#define EVER ;;

for (EVER)
{
...
}

Apr 26th, 2005, 8:55 AM	#1
colt Newbie Join Date: Mar 2005 Posts: 7 Rep Power: 0	Returning a value from a variable to the main function Hi, I am having a big little problem to return to the main function, the value of a sum operation. As you can see in the code, all I want to do is to return the data contained in the 'res' variable (n1 + n2) to the main function. There I call the function SUM through a call function "SUM (int res); " to display in the end of the main function, the result of the sum: n1 + n2, but I get the following errors: test.c: In function `main': test.c:15: error: syntax error before "int" So what I am doing wrong? What I need to do to sucessfully be able to return the data contained in the res variable to the main function to finally see the result of the mathematical operation? Thanks in advance. [code]#include <stdio.h> int SUM (int n1, int n2); main () { int n1, n2, i; while (5 == 5) { printf ("To close the program, type 0: "); scanf ("%d", &i); if (i == 0) break; printf ("Type the numbers that should be used to do the sum: "); scanf ("%d %d", &n1, &n2); SUM (int res); } } int SUM (int n1, int n2) { int res; res = n1 + n2; printf ("The result is: %d", res); return res; }

Apr 26th, 2005, 9:34 AM	#2
Eggbert Professional Programmer Join Date: Nov 2004 Posts: 250 Rep Power: 5	>while (5 == 5) { This is strange. Not only that you used <constant> == <constant>, but because you chose 5 as the constant. A more conventional way to create an infinite while loop is (Toggle Plain Text) while ( 1 ) { /* Body / } while ( 1 ) { / Body */ } >SUM (int res); A function call does not declare parameters, it takes arguments: (Toggle Plain Text) SUM (n1, n2); SUM (n1, n2); Here is the same program with the necessary fixes: (Toggle Plain Text) #include <stdio.h> int SUM (int n1, int n2); int main () { int n1, n2, i; while (1) { printf ("To close the program, type 0: "); scanf ("%d", &i); if (i == 0) break; printf ("Type the numbers that should be used to do the sum: "); scanf ("%d %d", &n1, &n2); SUM (n1, n2); } } int SUM (int n1, int n2) { int res; res = n1 + n2; printf ("The result is: %d", res); return res; } #include <stdio.h> int SUM (int n1, int n2); int main () { int n1, n2, i; while (1) { printf ("To close the program, type 0: "); scanf ("%d", &i); if (i == 0) break; printf ("Type the numbers that should be used to do the sum: "); scanf ("%d %d", &n1, &n2); SUM (n1, n2); } } int SUM (int n1, int n2) { int res; res = n1 + n2; printf ("The result is: %d", res); return res; }

Apr 28th, 2005, 8:11 AM	#3
mackenga Professional Programmer Join Date: Mar 2005 Location: Glasgow, Scotland Posts: 328 Rep Power: 4	Nice solution. I just thought I'd add; another conventional way to do an infinite loop is for (;;), which arguably is even clearer since it doesn't even have the 'dummy condition' constant 1. Last edited by mackenga; Apr 28th, 2005 at 8:11 AM. Reason: Darn smileys... :)

Apr 28th, 2005, 8:56 AM	#4
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,473 Rep Power: 8	Speaking of infinite loops... here's the "cool" way... #define EVER ;; for (EVER) { ... } __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

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Programming Forums > Application Development > C

Returning a value from a variable to the main function