#include <iostream>

 using namespace std;

 int main() {

     int a1 = ;

     int b1 = ;

     cout << a1 + b1 << endl;

     cout << a1 - b1 << endl;

     cout << a1 * b1 << endl;

     cout << a1 / b1 << endl;  //两个整数相除结果依然是整数

     int a2 = ;

     int b2 = ;

     cout << a2 / b2 << endl; 

     int a3 = ;

     int b3 = ;

     //cout << a3 / b3 << endl; //报错，除数不可以为0

     //两个小数可以相除

     double d1 = 0.5;

     double d2 = 0.25;

     cout << d1 / d2 << endl;

     system("pause");

     return ;

 }

 int main() {

     int a1 = ;

     int b1 = ;

     cout <<  %  << endl;

     int a2 = ;

     int b2 = ;

     cout << a2 % b2 << endl;

     int a3 = ;

     int b3 = ;

     //cout << a3 % b3 << endl; //取模运算时，除数也不能为0

     //两个小数不可以取模

     double d1 = 3.14;

     double d2 = 1.1;

     //cout << d1 % d2 << endl;

     system("pause");

     return ;

 }

 int main() {

     //后置递增

     int a = ;

     a++; //等价于a = a + 1

     cout << a << endl; // 11

     //前置递增

     int b = ;

     ++b;

     cout << b << endl; // 11

     //区别

     //前置递增先对变量进行++，再计算表达式

     int a2 = ;

     int b2 = ++a2 * ;

     cout << b2 << endl;

     //后置递增先计算表达式，后对变量进行++

     int a3 = ;

     int b3 = a3++ * ;

     cout << b3 << endl;

     system("pause");

     return ;

 }