#include<iostream>
using namespace std;
int area(int x, int y)
{
int a;
a = x * y;
return a;
}
int main()
{
int length, width;
cout << "请输入长方形的长度和宽度：";
...
#include<iostream>
using namespace std;
int main()
{
int x,a, b, c;
for (x = 100; x < 1000; x = x + 1)
{
a = x / 100;
b = (x / 10) % 10;
c = (x % 10);
...