Using variables

Question

I have a problem with this simple program because it doesnt give me the true outcome. I just want to sum two arguments in the first function and then use the outcome in the second one. It will be nice to have overall outcome in the main function. Also I would like to ask the same question with arrays.

#include <stdio.h>
#include <stdlib.h>

int sum()
{
int a=2;
int b=3;
int s=a+b;
printf("sum=%d\n",s);
return s;
}

int sum2(int s)
{
int c=5;
int d=c+s;

}


int main(int s,int d)
{
sum();

printf("sum=%d\n",s);

printf("sum2=%d\n",d);

getchar();
return 0;
}

seems like you are not using sum2 in the pgm..

Mithun Satheesh
– Mithun Satheesh

2011-08-27 12:30:59 +00:00
Commented Aug 27, 2011 at 12:30 — Mithun Satheesh
– Mithun Satheesh, Commented Aug 27, 2011 at 12:30

Oliver Charlesworth · Accepted Answer · 2011-08-27 12:30:57Z

3

There are many problems with this code:

int main(int s, int d) won't do what you think. Command-line arguments to your program come in string format. So you would need to use int main(int argc, char *argv[]).
The variables s and d in main() are completely independent to the variables in sum() and sum2(). So changing their values in those functions will not affect the original variables.
You're not even calling the second function!

You can do things like this:

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

int sum2(int c)
{
    return c+5;
}

int main(void)
{
    int x = 2;
    int y = 3;
    int z = sum(x,y);
    int w = sum2(z);
    printf("z = %d\n", z);
    printf("w = %d\n", w);
}

answered Aug 27, 2011 at 12:30

Oliver Charlesworth

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Comments

Saurabh Gokhale · Accepted Answer · 2011-08-27 12:31:13Z

1

First of all, s is a local variable inside sum( ). Hence it cannot be available outside the function.

int sum() {   
   // ..  
   int s = a+b; // local variable, hence local scope  
  // .. 
 }

Also, secondly, int main(int s,int d) won't work since in command line arguments come in String format. So can't use a int there

answered Aug 27, 2011 at 12:31

Saurabh Gokhale

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Comments

Preet Sangha · Accepted Answer · 2011-08-27 12:32:52Z

1

I won't tell you the answer (lol but others have) but I'll give you these clues to figuring it out.

Ask your self which functions are returning data and which ones aren't.

Clue: the function needs a return to return some data.

Then ask yourself which functions' returns are actually being used.

Clue: to collect the data returned from a function you need to assign the result to a variable like so

  int i;
  i = somefunct();

answered Aug 27, 2011 at 12:32

Preet Sangha

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Comments

JJ. · Accepted Answer · 2011-08-27 12:46:17Z

0

You can't access the value of variable 's' outside the function sum() since it is out of scope. You'll have to return the value to your main() function. Also your main function parameters are incorrect. You need something more like this:

#include <stdio.h>
#include <stdlib.h>

int sum(int a, int b)
{
    int s=a+b;
    printf("sum=%d\n",s);
    return s;
}

int sum2(int c, int sum)
{
    return c+sum;
}


int main(int argc, char *argv[])
{
    int val1 = sum(2, 3);
    printf("sum=%d\n",val1);

    int val2 = sum2(5, val1);
    printf("sum2=%d\n", val2);

    getchar();
    return 0;
}

edited Aug 27, 2011 at 12:46

answered Aug 27, 2011 at 12:32

JJ.

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