#include<stdio.h>
long square(long);//聲明函數
void main()
{  long in_num,result;
   printf("Input an integer:");
   scanf("%ld",&in_num);
   result=square(in_num);//函數調用
   printf("The square number of %ld is %ld\n",in_num,result);
}
long square(long x)//函數首部
{  long x_square;//說明部分
   x_square=x*x;//執行部分
   return x_square;
}