Arithmetic Operator
| Operator | Calculation | example | result | Remarks |
| + | Positive sign | +3 | 3 | |
| plus | 3+5 | 8 | ||
| - | negative | b=4;-b; | -4 | |
| Less | 5-3 | 2 | ||
| * | Multiply | 3*4 | 12 | |
| / | except | 10/5 | 2 | |
| % | Modulus (ie take the remainder) | 13%5 | 3 | |
| ++ | Self-increasing (front) | a=2; b=++a; | a=3; b=3 | Increment first, then calculate |
| Self-increasing (after) | a=2; b=a++; | a=3; b=2 | Calculate first, then increment | |
| -- | Decrement (front) | a=2; b=--a; | a=1; b=1 | Decrease first, then calculate |
| Decrement (post) | a=2; b=a--; | a=1; b=2 | Calculate first, then subtract |
table of Contents
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+ Operator
(1) Display positive number
(2) Represents the addition operation
(3) Concatenate strings
public class TestOpe01{
public static void main(String[] args){
//表示正数
System.out.println(+5); //5
//表示相加操作
System.out.println(5+6); //11
System.out.println(5+'6'); //5+54——>59
//字符串的拼接
/*
规则：+左右两侧的任意一侧有字符串，
那么这个加号就是字符串拼接的作用，
结果一定是字符串
*/
int num=50;
System.out.println("num="+num); //num=50
System.out.println(5+6+"7"); //11+"7"——>"117"——>117
System.out.println(5+'6'+"7"); //5+54+"7"——>59+"7"——>"597"——>597
System.out.println("5"+6+"7"); //"56"+"7"——>"567"——>567
System.out.println("5"+'6'+"7"); //"56"+"7"——>"567"——>567
System.out.println("5"+'6'+'7'); //"56"+'7'——>"567"——>567
}
}-
Division operator (/)
In the division operation, when the divisor and the dividend are both integers , the result obtained is also an integer ;
If a decimal is involved in the division operation , the result will be a decimal .
public class TestOpe02{
public static void main(String[] args){
System.out.println(12/3); //4
System.out.println(12/3.0); //4.0
}
}-
Modulus operator (%)
When performing modulo operation, the sign of the result depends on the sign of the modulus ( the number to the left of % ). It has nothing to do with the sign of the modulus (the number to the right of %).
For example, the result of (-5)%3 is -2, and the result of 5%(-3) is 2.
public class TestOpe03{
public static void main(String[] args){
System.out.println(-5%3); //-2
System.out.println(-5.0%3); //-2.0
System.out.println(5%-3); //2
System.out.println(5.0%-3); //2.0
}
}-
Exercise 1 (/and %)
public class TestOpe04{
public static void main(String[] args){
//实现功能：任意给出一个四位数，求出每位上的数字并输出
//任意给出一个四位数
int num=2345;
//求出每位上的数字
int num1=num%10; //2345——>5
int num2=num/10%10; //2345——>234——>4
int num3=num/100%10; //2345——>23——>3
int num4=num/1000; //2345——>2
//输出每位上的数字
System.out.println("个位上的数字为："+num1); //个位上的数字为：5
System.out.println("十位上的数字为："+num2); //十位上的数字为：4
System.out.println("百位上的数字为："+num3); //百位上的数字为：3
System.out.println("千位上的数字为："+num4); //千位上的数字为：2
}
}Improvement: any number entered by the user
Introduce Scanner
import java.util.Scanner; public class TestOpe04{ public static void main(String[] args){ //实现功能：任意给出一个四位数，求出每位上的数字并输出 //任意给出一个四位数 Scanner input=new Scanner(System.in); System.out.println("请录入一个四位数："); int num=input.nextInt(); //求出每位上的数字 int num1=num%10; int num2=num/10%10; int num3=num/100%10; int num4=num/1000; //输出每位上的数字 System.out.println("个位上的数字为："+num1); System.out.println("十位上的数字为："+num2); System.out.println("百位上的数字为："+num3); System.out.println("千位上的数字为："+num4); } }
-
Increment (++) operator
When performing an increment ++ or decrement - operation, no matter whether the variable is involved in the operation, as long as the ++ operator is used , the variable itself will eventually be incremented by 1 .
If ++ is at the end, calculate first, then add 1; if ++ is at the front, add 1 first, then calculate.
public class TestOpe05{
public static void main(String[] args){
int a=5;
a++;
System.out.println(a); //6
a=5;
++a;
System.out.println(a); //6
/*
总结：无论这个变量是否参与到运算中去，
只要用++运算符，这个变量本身最终都加1操作。
*/
a=5;
int m=a+++7; //先运算m=a+7 ,再自增a=a+1。
System.out.println(m); //12
System.out.println(a); //6
a=5;
int n=++a+7; //先自增a=a+1 ,再运算n=a+7。
System.out.println(n); //13
System.out.println(a); //6
}
}operation result:
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Exercise 2 (++)
public class TestOpe06{
public static void main(String[] args){
int a=5;
//注：运算符优先级 ++ > +
System.out.println(a++ + a++);
System.out.println(a++ + ++a);
System.out.println(++a + a++);
System.out.println(++a + ++a);
}
}Operation process:
Calculation result:
