While,DoWhile,for循环

public class WhileDemo03 {
    public static void main(String[] args) {
        //计算1-100的和
        int i=0;
        int sum=0;

        while (i<=100){
            sum=sum+i;
            i++;
        }
        System.out.println(sum);
    }
}

public class DoWhileDemo02 {
    public static void main(String[] args) {
        int a=0;
        while (a<0){
            System.out.println(a);//不输出
            a++;
        }
        System.out.println("====================");

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

    }
}

public class ForDemo01 {
    public static void main(String[] args) {
        int a=1;//初始化条件

        while(a<=100){//条件判断
            System.out.println(a);//循环体
            a+=2;//迭代
        }
        System.out.println("while循环结束");

        //初始化；条件判断；迭代
        for (int i=1;i<=100;i++){
            System.out.println(i);
        }
        System.out.println("for循环结束");

        //100.for
       // for (int i = 0; i < 100; i++) {}
        //死循环 for(,,);
    }
}

public class ForDemo02 {
    public static void main(String[] args) {
        //0-100 奇数偶数的和
        int oddSum=0;
        int evenSum=0;

        for (int i=0;i<=100;i++){
            if(i%2!=0){//奇数
                oddSum+=i;    //oddSum=oddSum+i;
            }else{//偶数
                evenSum+=i;
            }
        }
        System.out.println("奇数和："+oddSum);
        System.out.println("偶数和："+evenSum);

    }
}

public class ForDemo03 {
    public static void main(String[] args) {
        //输出1-1000之间能被5整除的数，并且每行输出三个
        for(int i=0;i<=1000;i++){
            if(i%5==0) {
                System.out.println(i+"\t");
            }
            if (i%(5*3)==0){
                System.out.println();//System.out.print("\n");
            }
        }
        //println输出完会换行
        //print输出完不会换行

    }
}

public class ForDemo04 {
    public static void main(String[] args) {
        //打印九九乘法表
        for(int j=1;j<=9;j++){
            for(int i=1;i<=j;i++){
                System.out.print(j+"*"+i+"="+(j*i)+"\t");
            }
            System.out.println();
        }
    }
}

public class ForDemo05 {
    public static void main(String[] args) {
        int[] numbers={10,20,30,40,50};//建了个数组,第一位是0

        for (int i=0;i<5;i++){
            System.out.println(numbers[i]);
        }
        //遍历数组的元素
        for(int x:numbers){//增强for循环
            System.out.println(x);
        }


    }
}