1. 闰年判断

知识点：

1. cout，cin，箭头方向
2. 创建简单的类和对象（纯纯力扣模板）
3. 主函数的return 0；

#include<iostream>
using namespace std;class Solution {public:void isLeap() {int year;bool isLeapYear;cout << "Enter the year: ";cin >> year;isLeapYear = (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);if (isLeapYear) {cout << year << " is a leap year." << endl;} else {cout << year << " is not a leap year." << endl;}}
};int main() {Solution solution;solution.isLeap();return 0;
}

2. 比较两个数的大小

知识点：

1. 连续输入用 >> 隔开，实际输入用空格隔开；
2. 两个及以上同类型变量声明用逗号；
3. if … else语句格式。

#include<iostream>
using namespace std;int main() {int x, y;cout << "Enter x and y: ";cin >> x >> y;if (x != y) {if (x > y) {cout<<"x > y"<<endl;} else {cout<<"x < y"<<endl;}} else {cout<<"x = y"<<endl;}return 0;
}

3. switch语句用法

1. 执行完需要break来退出switch
2. 没有符合要求的则执行default

#include<iostream>
using namespace std;int main() {int day;cout << "Enter the day: ";cin >> day;switch (day) {case 0:cout << "Sunday" << endl;break;case 1:cout << "Monday" << endl;break;case 2:cout << "Tuesday" << endl;break;case 3:cout << "Wednesday" << endl;break;case 4:cout << "Thursday" << endl;break;case 5:cout << "Friday" << endl;break;case 6:cout << "Saturday" << endl;break;	default:cout << "Day out of range Sunday ... Saturday" << endl; }
} 

4. 循环语句用法

知识点：

1. while
2. do … while 末尾结束要分号
3. for

#include<iostream>
using namespace std;int useWhile(int n) {int i = 1, sum = 0;while (i <= n) {sum += i;i++;}return sum;
}void useDoWhile(int n) {int cur;do {cur = n % 10;cout << cur;n /= 10;} while (n != 0);cout << endl;int i = 1, sum = 0;do {sum += i;i++;} while (i <= 100);cout << "sum = " << sum << endl;
}void useFor(int n) {for (int i = 1; i <= n; i++) {if (n % i == 0) cout << i << " ";}cout << endl;
}int main() {cout << useWhile(100) << endl;useDoWhile(102);useFor(24);return 0;
}

5. enum枚举

头是0，尾是n - 1

#include<iostream>
using namespace std;enum GameResult {WIN, LOSE, TIE, CANCEL};int main() {GameResult result;enum GameResult omit = CANCEL;for (int count = WIN; count <= CANCEL; count++) {result = GameResult(count);if (result == omit) cout << "The game was cancelled" << endl;else {cout << "The game was played ";if (result == WIN)cout << "and we won!";if (result == LOSE) cout << "and we lose.";cout << endl;}}return 0;
}

5. typedef声明

typedef 已有类型名 新类型名表;

#include<iostream>
using namespace std;int main() {typedef double Area;typedef unsigned Natural;Natural a, b;Area s;cin >> a >> b;cout << "s = " << a * b << endl;return 0;
}