day-04

運算符

package operator;

public class Demo01 {
    public static void main(String[] args) {
        //二進制運算符
        //ctrl+d 複制目前行到下一行
        int a =10;
        int b =20;
        int c =25;
        int d =30;
        System.out.println(a+b);
        System.out.println(a*b);
        System.out.println(a-b);
        System.out.println(a/b);
        System.out.println(a/(double)b);
    }
}
           

package operator;

public class Demo02 {
    public static void main(String[] args) {
        long a =1213132123414L;
        int b = 123;
        short c = 10;
        byte d =8;
        System.out.println(a+b+c+d);//long
        System.out.println(b+c+d);//int
        System.out.println(c+d);//int
    }
}
           

public class Demo03 {
    public static void main(String[] args) {
        //關系運算符傳回結果：正确 錯誤 布爾值
        int a =10;
        int b =20;
        int c =21;
        System.out.println(a>b);
        System.out.println(a<b);
        System.out.println(a==b);
        System.out.println(a!=b);
        System.out.println(c%a);//取餘
    }
}
           

public class Demo04 {
    public static void main(String[] args) {
        //++ -- 自增 自減
        int a =3;
        int b=++a;//先指派，再自增
        System.out.println(a);
        int c =a++;//先自增，再指派
        System.out.println(a);
        System.out.println(b);
        System.out.println(c);
        //幂運算  很多運算會使用工具類來做
        double pow = Math.pow(2,3);//alt+enter 引入局部變量
        System.out.println(pow);
    }
}
           

public class Demo05 {
    public static void main(String[] args) {
        // 與或非
        boolean a =true;
        boolean b =false;
        System.out.println("a&&b:"+(a&&b));
        System.out.println("a||b:"+(a||b));
        System.out.println("!a&&b:"+!(a&&b));

        //短路運算
        int c =5;
        boolean d =(c<4)&&(c++<4);
        System.out.println(d);
        System.out.println(c);
    }
}
           

public class Demo06 {
    public static void main(String[] args) {
        /*
        A=0011 1100
        B=0000 1101
      A&B=0000 1100
      A|B=0000 1101
      A^B=0011 0001
       ~B=1111 0010
       <<  *2  左移
       >>  /2  右移

       */
        System.out.println(2<<3);
    }
}
           

public class Demo07 {
    public static void main(String[] args) {
        int a=10;
        int b=20;
        a+=b;
        a-=b;
        System.out.println(b);
        //字元串連接配接符 +  , String
        System.out.println(a+b);//30
        System.out.println(""+a+b);//1020
        System.out.println(a+b+"");//30
    }
}
           

public class Demo08 {
    public static void main(String[] args) {
        //x?y:z
        //如果x為true，則傳回y，否則傳回z
        int score =80;
        String type =score<60?"不及格":"及格";//必須掌握
        System.out.println(type);
    }
}