Thread: Using functions

Hi guys, I'm learning how to do functions in my class now but i'm having a little trouble getting them to work.

Code:

void printFraction(int n, int d)
{
     printf("%d/%d",n,d);
}

void scanFraction(int a, int b)
{
     scanf("%d",&a);
     scanf("%d",&b);
}

char scanOperator(void)
{

}

int main(void)

{
    int a,b;
    printf("Enter the numerator and denominator of a common fraction: ");
    void scanFraction(int a,int b);
    printf("\n");
    if(b>0)
{
    printf("You have entered: ");
    void printFraction(int a,int b);
}
else if(b<=0)
{
    printf("The common fraction you entered is invalid.");
}

My first problem is just that It won't ask me to scan an integer, it skips the scanFraction functions and prints out the rest of my statements.

That's because you never actually call the function. You only have a function prototype.
To actually call a function, you need to use the syntax:
name_of_function(name_of_paramter1, ...);
Note that the type of the parameters shall NOT be included. Nor shall the return type of the function.
You may wish to review this in your book.

Also, << !! Posting Code? Read this First !! >>.

You may wish to improve indentation, as well.
Also note that ScanFraction will not work properly without pointers.

So far so good, but I don't know what to do for this next part where i am asking the user to enter an arithmatic operator (+, -, *, /)...

Code:

void printFraction(int n, int d)
{
     printf("%d/%d",n,d);
}

void scanFraction(int *n, int *p)
{
     scanf("%d %d",&*n,&*p);
}

char scanOperator(void)
{
     char c;
     scanf("%c",&c);
}

int main(void)

{
    int a,b;
    char c;
    printf("Enter the numerator and denominator of a common fraction: ");
    scanFraction(&a,&b);
    for(;b<=0;)
{   
    printf("The common fraction you entered is invalid.\n");
    printf("Enter the numerator and denominator of a common fraction: ");
    scanFraction(&a,&b);
}
    printf("You have entered: ");
    printFraction(a,b);
    printf("\n");
    printf("Enter an arithmetic operator (+, -, *, /): ");
    scanOperator();
system("PAUSE");
return 0;
}

The output should look something like this:

Enter an arithmetic operator (+, -, *, /): .<enter>
The arithmetic operator you entered is invalid.
Enter an arithmetic operator (+, -, *, /): *<enter>
You have entered: *

where the orange is user input.

Well guys I finished! Including the other parts to the program I didn't mention. Thanks for you're advise Elysia