JAVA笔记-运算符-分支结构

前缀 ++ -- 先加一后使用

后缀++ -- 先使用后加一 

public class TestOperator {
	public static void main(String[] args) {
        int a = 4;
		int b;
		int c;
		b = a++;
		System.out.println("后缀先赋值后加一");
		System.out.println(b);
		System.out.println(a);
		System.out.println("前缀先加一后赋值");
	    a = 4;
		c = ++a;
		System.out.println(c);
		System.out.println(a);
	}
}

import java.util.Scanner;
public class TestMaxNum {
	public static void main(String[] args) {
		System.out.println("请输入第一个数字a");
		int a = new Scanner(System.in).nextInt();
		System.out.println("请输入第二个数字b");
		int b =  new Scanner(System.in).nextInt();
		int max = a>b?a:b;
		System.out.println("a和b中较大的数值为："+ max);
	}
}

public class TestScore {
	public static void main(String[] args) {
		System.out.println("请输入分数：");
		int score = new Scanner(System.in).nextInt();
		if(score<0 || score >100) {
			System.out.println("输入的分数不正确，请重新输入！");
		}else {
			if(score >= 90) {
				System.out.println("宰相");
			}else if(score >= 80) {
				System.out.println("尚书");
			}else if(score >=70) {
				System.out.println("大夫");
			}else if(score >= 60) {
				System.out.println("都督");
			}else {
				System.out.println("准备科举");
		}
		}
	}
}

public class TestSwitch {
	public static void main(String[] args) {
		int a = new Scanner(System.in).nextInt();
		switch(a) {
			case 1 : System.out.println(1); break;
			case 2 : System.out.println(2); break;
			case 3 : System.out.println(3); break;
			case 4 : System.out.println(4); break;
			case 5 : System.out.println(5); break;
			default : System.out.println(0); break;
		
		}
	}
}

public class Test99ForExcel {
	public static void main(String[] args) {
		for(int i = 1 ;i < 10;i++) {
			for(int j = 1 ;j<=i;j++) {
				System.out.print(j+"*"+i+"="+i*j+"t");
			}
			System.out.println();	
		}
	}

}

/t 制表符  快捷键：alt+ctrl+下页 复制前面一行

while 循环 

public class TestWhile {
	public static void main(String[] args) {
		int r = new Random().nextInt(100);//随机数含头不含尾
		System.out.println(r);
		
		while(true) {
	     System.out.println("请输入你猜想的数值：");
		 int input = new Scanner(System.in).nextInt();
		 if(input>r) {
			 System.out.println("猜大了");			 
		 }else if(input < r) {
			 System.out.println("猜小了");
		 }else {
			 System.out.println("恭喜你你中将了");
			 break;
		 }
		}
	}
}

public class TestDoWhile {
	public static void main(String[] args) {
		int n;
		do {
			n = new Random().nextInt(300);
			System.out.println(n);
		}while(n>100);
	}
}