for循环练习题

练习1:计算0到100之间的奇数和偶数的和:

package struct;

public class ForDemo02 {
    public static void main(String[] args) {
        //练习1:计算0到100之间的奇数和偶数的和
        int oddSum = 0;
        int evenSum =0;
        for (int i = 0;i<100;i++){
            if (i%2!=0){//奇数
                oddSum+=i;
            }else{//偶数
                evenSum+=i;
            }
        }
        System.out.println("奇数的和:"+oddSum);
        System.out.println("偶数的和:"+evenSum);
    }
}

练习2:用while或for循环输出1-1000之间能被5整除的数,并且每行输出三个:

package struct;

public class ForDemo03 {
    public static void main(String[] args) {
        //练习2:用while或for循环输出1-1000之间能被5整除的数,并且每行输出三个
        for (int i = 1; i <= 1000; i++) {
            if (i%5==0){
                System.out.print(i+"\t");
            }
            if (i%(5*3)==0){//换行
                System.out.println();
                //System.out.print("\n");
            }
        }
        //println 输出完会换行
        ///print 输出完不会换行
    }
}

九九乘法表:

package struct;

public class ForDemo04 {
    public static void main(String[] args) {
        //1.我们先打印第一列
        //2.我们把固定的1再用一个循环包起来
        //3.去掉重复项,i<=j
        //4.调整样式
        for (int j = 0; j <= 9; j++) {
            for (int i = 0; i <= j; i++) {
                System.out.print(j+"*"+i+"="+(j*i)+"\t");
            }
            System.out.println();
        }
    }
}

package struct;

public class LabelDemo {
    public static void main(String[] args) {
        //打印101-150之间所有的质数
        int count = 0;
        outer:for (int i = 101; i < 150; i++) {
            for (int j = 2;j<i/2;j++){
                if (i % j == 0){
                    continue outer;
                }
            }
            System.out.print(i+" ");
        }
    }
}

打印三角形:

package com.kuang.Struct;

public class TestDemo01 {

    public static void main(String[] args) {
        //打印三角形   5行

        for (int i = 0; i <= 5; i++) {
            for (int j = 5;j>=i;j--){
                System.out.print(" ");
            }
            for (int j = 1;j<=i;j++){
                System.out.print("*");
            }
            for (int j = 1; j <i ; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}