For循环

package Struck;

public class ForDemo01 {
    public static void main(String[] args) {
        int a = 0;//初始化条件
        while(a<100){//循环体
            System.out.println(a);
            a++;//对a的更新or迭代
        }
        System.out.println("while循环结束！");
        //初始化//条件判断//更新
        for(int i=1;i<80;i++){
            System.out.println(i);
        }
        System.out.println("for循环结束！");
    }
}
===================================================================================

package Struck;

public class ForDemo02 {
    public static void main(String[] args) {
        //题：计算0-100之间奇偶数的和
        int oddsum = 0;
        int evensum = 0;

        for (int i = 0; i <= 100; i++) {
            if(i%2!=0){//奇数
                oddsum+=i;
            }else{
                evensum+=i;
            }
        }
        System.out.println(oddsum);
        System.out.println(evensum);
    }
}

===================================================================================

package Struck;

public class ForDemo03 {
    public static void main(String[] args) {
        //题：用while或for循环输出1-1000之间被5整除的数，且每行输出三个

        for (int i = 0; i <= 1000; i++) {
            if(i%5==0) {
                System.out.print(i+"\t");//转义字符\t
            }
            if(i%(5*3)==0){//每行
                System.out.println();//输出空串为换行
                //System.out.print("\n");
            }
        }
        //println  输出完会换行
        //print  输出完不会换行
    }
}

===================================================================================

package Struck;

public class ForDemo04 {
    public static void main(String[] args) {
        //1:先打印第一列
        //2:再用一个循环把固定好的第一列包起来
        //3:去除掉重复项
        //4:调整样式
        for (int s = 1; s <= 9; s++) {
            for (int i = 1; i <= s; i++) {
                System.out.print(s+"*"+i+"="+(s*i) + "\t");
            }
            System.out.println();
        }
    }
}

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