#include <stdio.h>
#include <conio.h>
double square(double);
int main (void)
{
  double x,squ;
  printf ("請輸入一數字: ");
  scanf ("%lf",&x);
  
  squ=square(x);
  
  printf ("此數平方為: %lf",squ);
  
  getch ();
  return 0;
}

double square (double x)
{
  double a=1.0;
  a=x*x; 
  return a; 
}