really simple question

[JezW]

i am trying to return the result "c" back to the main function. can anyone see why this isn't printing the correct answer the second time?

thanks, jez

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

int divide(float c);


int main()
{
    float fraction;

    divide(fraction);
    printf("%f",fraction);

return 0;
}

int divide(float c)
{
    float a, b;

    scanf("%f",&a);
    scanf("%f",&b);
    c=a/b;
    printf("%f\n",c);
    return(c);
}

[BEN10]

initialize fraction with a value in main and also return 0 at the end of main().u're also not saving the returned vlaue from divide in some variable in main().

[JezW]

initialize fraction with a value in main and also return 0 at the end of main().u're also not saving the returned vlaue from divide in some variable in main().

sorry mate i don't understand. do u mean this:

#include <stdio.h>
#include <stdlib.h>
int divide(float c);


int main(float fraction)
{


    divide(fraction);
    printf("%f",fraction);

    return 0;
}

int divide(float c)
{
    float a, b;

    scanf("%f",&a);
    scanf("%f",&b);
    c=a/b;
    printf("%f\n",c);
    return(c);
}

because it doesn't work either!

[grumpy]

Simple answer to your original question: yes.

Just in case you really want a slightly more illuminating response, I'll point out that the function divide accepts its argument by value. Which means that the call divide(fraction) passes a copy of the value of fraction. The changes of c within divide() are local to that function, and therefore not visible in main().

Two (of many) options to do what you want are;

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

float divide();

int main()
{
    float fraction;

    fraction = divide();
    printf("%f",fraction);

return 0;
}

float divide()
{
    float a, b;

    scanf("%f",&a);
    scanf("%f",&b);
    c=a/b;
    printf("%f\n",c);
    return(c);
}

or (passing pointers around, not values).

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

int divide(float *c);

int main()
{
    float fraction;

    divide(&fraction);
    printf("%f",fraction);

return 0;
}

int divide(float *c)
{
    float a, b;

    scanf("%f",&a);
    scanf("%f",&b);
    *c=a/b;
    printf("%f\n",*c);
    return(*c);   / *I won't even speculate why you're converting the value you calculate to an int */
}

[BEN10]

No.i mean in the line where u declare fraction in main() do this.

float fraction=0.0;//anything here to initialize

also do this to print the correct value.

printf("%d",divide(fraction));

[JezW]

thanks for the replys guys.

"/ *I won't even speculate why you're converting the value you calculate to an int */"

I thought "int" was how you defined a function!?

[EVOEx]

I thought "int" was how you defined a function!?

No. That's how you tell the compiler: the function returns an integer. You can change it to any type.

[JezW]

thanks guys i know this is really basic stuff but i do appreciate it and its very helpful

Jez

[JezW]

The program i am writing takes in 6 strings a0,b0,c0,x0,y0 and z0. It then converts them to doubles a,b,c,x,y,z using the atof function. if the user types "f" then it goes to the divide function that returns a float so there is no need for the atof.

I am trying to create a for loop to cut down unnecessary code

Instead of:

    printf("A = ");
    scanf("%s",a0);

    if (strcmpi("f",a0)==0)
        {
            a=divide();
        }
    else
        {
            a=atof(a0);
        }

For a,b,c,x,y,z^^^^^

I would like something like this:

    for (i=0;i<6;i++)

        {
        if (i==0) {
                  sprintf(variable,'a');
                  sprintf(variable0,'a0');
                  }
        if (i==1) {
                  sprintf(variable,'b');
                  sprintf(variable0,'b0');
                  }
        if (i==2) {
                  sprintf(variable,'c');
                  sprintf(variable0,'c0');
                  }
        if (i==3) {
                  sprintf(variable,'x');
                  sprintf(variable0,'x0');
                  }
        if (i==4) {
                  sprintf(variable,'y');
                  sprintf(variable0,'y0');
                  }
        if (i==5) {
                  sprintf(variable,'z');
                  sprintf(variable0,'a0');
                  }

        printf("\n                                      %s = ", variable);
        scanf("%s",variable0);

        if (strcmpi("f",*variable0)==0)
            {
                *variable=divide();
            }
        else
            {
                *variable=atof(variable0);
            }

        }

I know the code is quite bad but hopefully you can see what i am trying to do. I am literally trying to replace the word "variable" with a,b,c,x,y,z and i know it won't work. I had a go with pointers too - it got the program running but it crashes straight away.


Thanks for all the help,

Jez