DoWhile循环

package com.chenao.struct;

public class DoWhileDemo01 {
    public static void main(String[] args) {

        // while如果不满足条件，则不能进入循环，do...while循环至少会执行一次

        /*
        1.while 先判断后执行， do...while 先执行后判断
        2.do...while 总是保证循环体会被至少执行一次
         */

        int i = 0;
        int sum = 0;

        //先执行
        do {
            sum = sum + i;
            i++;
        }while (i<=100);  //后判断

        System.out.println(sum );
    }
}

package com.chenao.struct;

public class DoWhileDemo02 {
    public static void main(String[] args) {
        int a = 0;

        while (a<0){
            System.out.println(a);
            a++;
        }
        System.out.println("=====================================");

        do {
            System.out.println(a);
            a++;
        }while(a<0);
    }

}

package com.chenao.struct;

public class DoWhileDemo03 {
    public static void main(String[] args) {

        //计算 1+...100=?
        int a = 0;
        int sum = 0;

        do {
            sum = sum + a;
            a++;
        }while (a>100);
        System.out.println(sum);
        System.out.println("==================");

        while (a<=100){
            sum = sum + a;
            a++;

        }
        System.out.println(sum);

    }
}