Squaring

#include "stdio.h"
double square(double v)
{
   return v*v;
   /*
   double ans;
   ans=v*v;
   return ans*/
}
int main (void)
{
    double val;
    printf("Please enter a number:\n");
    scanf("%lf", &val);
    printf("Square of %lf is %lf\n",val,square(val));
    system("pause");
    return 0;
}