Question

I have a recursive program. When the printf is used in the function, it outputs 123 and when used outside, it outputs 0123 .

#include <stdio.h>

fact(int);
int main()
{
    int x=3;
    fact(x);
    printf("\n");
    system("PAUSE");
}

int fact(int y)
{
    if (y > 0)
    {
         fact(y-1);
         printf("%d",y);  
    }
    //printf("%d",y);   
}   

I am not using both the printf at the same time . What difference does the location of this printf statement create?

Answer 1

fact(int) is called by following sequence,

fact(3)–>fact(2)—>fact(1)—>fact(0)

The last call is fact(0). According to the implementation of fact(int), when 0 is passed in, 0 is printed if printf() is used outsite. 0 is not printed if printf() is used inside.

In fact, all the values passed into fact(int) is printed when printf() is used outsite.