java 选择与循环

1.选择判断

public static void main(String[] args) {
System.out.println("请输入4位会员卡号");
Scanner scr = new Scanner(System.in);
int a = scr.nextInt();
int a = a%10;
int b = a/10%10;
int cc= a/100%10;
int d = a/1000;
int sum = a+b+c+d;

System.out.println("会员卡号"+a+"各位之和:"+sum);
if(sum>20){
System.out.println("是幸运客户");
}else{

System.out.println("不是是幸运客户");

}

2.循环输出（输出等于输入数字及加数小于或等于输入数字的等式）

public static void main(String[] args) {
System.out.println("请输入数字");
Scanner sca = new Scanner(System.in);
int a = sca.nextInt();
for(int i=0;i<=a;i++){

System.out.println(i+"+"+(a-i)+"="+a);
}
}