2.1重学C++之【选择结构：if、三目运算符、switch】

#include<iostream>
#include<string>
using namespace std;


int main(){
    //程序流程结构：顺序结构 选择结构 循环结构

    //1 选择结构

    //1-1单行if语句 if(){}
    //1-2多行if语句 if(){}else{}
    //1-3多条件if语句 if(){}else if(){}...else{}
    //1-4嵌套if语句 if(){ if(){} }


    //1-5三目运算符?:
    //a和b比较，值大的变量赋值给c
    int a = 10, b = 20, c = 0;
    c = (a > b ? a : b);
    cout << c << endl;
    //C++中三目运算符返回的是变量，可以继续赋值
    (a < b ? a : b) = 100;
    cout << "a=" << a << endl;
    cout << "b=" << b << endl;


    //1-6switch
    int score = 0;
    cout << "请给电影打分（1-10）：" << endl;
    cin >> score;
    switch(score){  // 缺点：判断条件只能为整型/字符型，不可以是区间；优点：结构清晰运行效率高
    case 10:
        cout << "经典电影" << endl;
        break;
    case 9:
        cout << "电影非常好" << endl;
        break;
    case 8:
        cout << "电影还不错" << endl;
        break;
    case 7:
        cout << "电影一般" << endl;
        break;
    case 6:
        cout << "及格电影" << endl;
        break;
    default:
        cout << "烂片" << endl;
        break;
    }


    return 0;
}