Java基础语法 运算符定义和算数运算符

运算符定义

算数运算符

%:取余运算

结果的符号与被模数的符号相同
开发中，经常使用%来判断能否被除尽的情况。

自增和自减

(前)++ :先自增1，后运算

(后)++ :先运算，后自增1

(前)-- :先自减1，后运算

(后)-- :先运算，后自减1

注意问题

package BasicGrammar.day03;
/*
运算符之一：算术运算符
+ - + - * / % (前)++ (后)++ (前)-- (后)-- +

*/
public class AriTest {
    public static void main(String[] args) {
        //除号：/
        int num1 = 12;
        int num2 = 5;
        int result1 = num1 / num2;
        System.out.println(result1);//2

        int result2 = num1 / num2 * num2;
        System.out.println(result2);//10

        double result3 = num1 / num2;
        System.out.println(result3);//2.0

        double result4 = num1 / num2 + 0.0;//2.0
        double result5 = num1 / (num2 + 0.0);//2.4
        double result6 = (double)num1 / num2;//2.4
        double result7 = (double)(num1 / num2);//2.0
        System.out.println(result5);
        System.out.println(result6);

        // %:取余运算
        //结果的符号与被模数的符号相同
        //开发中，经常使用%来判断能否被除尽的情况。
        int m1 = 12;
        int n1 = 5;
        System.out.println("m1 % n1 = " + m1 % n1);

        int m2 = -12;
        int n2 = 5;
        System.out.println("m2 % n2 = " + m2 % n2);

        int m3 = 12;
        int n3 = -5;
        System.out.println("m3 % n3 = " + m3 % n3);

        int m4 = -12;
        int n4 = -5;
        System.out.println("m4 % n4 = " + m4 % n4);


        //(前)++ :先自增1，后运算
        //(后)++ :先运算，后自增1
        int a1 = 10;
        int b1 = ++a1;
        System.out.println("a1 = " + a1 + ",b1 = " + b1);

        int a2 = 10;
        int b2 = a2++;
        System.out.println("a2 = " + a2 + ",b2 = " + b2);

        int a3 = 10;
        ++a3;//a3++;
        int b3 = a3;

        //注意点：
        short s1 = 10;
        //s1 = s1 + 1;//编译失败
        //s1 = (short)(s1 + 1);//正确的
        s1++;//自增1不会改变本身变量的数据类型
        System.out.println(s1);

        //问题：
        byte bb1 =127;
        bb1++;
        System.out.println("bb1 = " + bb1);

        //(前)-- :先自减1，后运算
        //(后)-- :先运算，后自减1

        int a4 = 10;
        int b4 = a4--;//int b4 = --a4;
        System.out.println("a4 = " + a4 + ",b4 = " + b4);

    }
}