zj-Exercise/java-Eclipse/day03/AriTest.java.bak

/*
运算符之一：算术运算符
+ - + - * / % （前）++ （后）++ （前）-- （后）-- +


*/
class AriTest{
	public static void main(String[] args){

		//除号：/
		int num1 = 12;
		int num2 = 5;
		int result = num1/num2;
		System.out.println(result);//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

		//%: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);//2

		int m2 = -12;
		int n2 = 5;
		System.out.println("m2 % n2="+m2 % n2);//-2

		int m3 = 12;
		int n3 = -5;
		System.out.println("m3 % n3="+m3 % n3);//2

		int m4 = -12;
		int n4 = -5;
		System.out.println("m4 % n4="+m4 % n4);//-2

		//（前）++：先自增1，然后再运算
		//（后）++ ：先运算，后自增1
		int a1 = 10;
		int b1 = ++a1;
		System.out.println("a1="+ a1 + ",b1="+b1);//11,11

		int a2 = 10;
		int b2 = a2++;
		System.out.println("a2="+ a2 + ",b2="+b2);//11,10

		int a3 = 10;
		a3++;
		int b3 = a3;//11

		//注意点：
		short s1 = 10;
		//s1 = s1 + 1;//编译失败
		s1 = (short)(s1 + 1);//正确
		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);//-128



		//（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);

	}
}