Java provides a rich set of operators to manipulate variables. We can divide operators into the following groups:
Arithmetic operators
Relational operators Bitwise
operators
Logical operators
Assignment operators
Other operators
- Increment/decrement
Java provides ++ operation and – operation, which can add 1 and subtract 1 to an integer:
public class Test01 {
public static void main(String[] args) {
/**
* 等于号表示赋值的意思，即 右边赋值到左边
* i++ 先赋值，后运算；
* ++i 先运算，后赋值；
*/
int i = 0;
// i = i++;//0
i = ++i;//1
System.out.print(i);
}
}
public class Test02 {
public static void main(String[] args) {
//自增 ++ ；自减--
/**
* 总结：
* 自增自减在变量后时，直接返回等于号左边值（注：等于号表示赋值从右往左）
* 自增自减在变量前时，等于号两边值都改变一致
*
* ++出现在变量后，先赋值，再对变量中保存的值进行自加1运算
* ++出现在变量前，先进行自加1运算，再赋值
*
* --出现在变量后，先赋值，再对变量中保存的值进行自减1运算
* --出现在变量前，先进行自减1运算，再赋值
*/
int a = 100;
int b = a++;//a = 101 || b = 100
//int b = ++a;//a = 101 || b = 101
//int b = a--;//a = 99 || b = 100
//int b = --a;//a = 99 || b = 99
System.out.println(a);
System.out.println(b);
}
}
public class Test03 {
public static void main(String[] args) {
//++出现在变量后，先赋值，在对变量中保存的值进行自加1运算
int a = 100;
int b = a++;
System.out.println(a); //101
System.out.println(b); //100
//++出现在变量前，先进行自加1运算，在赋值
int m = 10;
int n = ++m;
System.out.println(m);//11
System.out.println(n);//11
int x = 500;
System.out.println(x++);//500
System.out.println(x);//501
int y = 100;
System.out.println(++y);//101
System.out.println(y);//101
//出现在变量后，先赋值，在对变量中保存的值进行自减1运算
int c = 100;
int d = c--;
System.out.println(c); //99
System.out.println(d); //100
//出现在变量前，先进行自减1运算，在赋值
int e = 10;
int f = --e;
System.out.println(e);//9
System.out.println(f);//9
}
}
public class Test04{
public static void main(String[] args) {
// 自增/自减运算
int n = 666;
n++; // 667, 相当于 n = n + 1;
n--; // 666, 相当于 n = n - 1;
int y = 100 + (++n); // n = 1 + n;即 100 + (1+666)
System.out.println(y);
}
}
》》》Expansion practice examples
public class Test05 {
public static void main(String[] args) {
// a 的值为多少？
int a = 1;
a+=4;
//a-= 4;
System.out.println(a);
}
}
public class Test06 {
public static void main(String[] args) {
// a b 的值各为多少？
int a = 1;
int b = a++ + ++a;
System.out.println(a);
System.out.println(b);
}
}
It can be seen from the above: a++ + ++a -> 2 + 1 -> a = 3 -> b = 1 + 3 -> b = 4
public class Test07 {
public static void main(String[] args) {
// a b c d的值各为多少？
int a = 1;
int b = 2;
int c = 3;
int d = a++ + ++b * c-- - ++a / b-- + ++c;
System.out.println(a);//3
System.out.println(b);//2
System.out.println(c);//3
System.out.println(d);//12
}
}
public class Test08 {
public static void main(String[] args){
int a = 1;
int b = a++; // b = 1, a = 2
int c = ++b; // c = 2, b = 2
int d = c--; // d = 2, c = 1
int e = --d; // e = 1, d = 1
// 2 2 2 0 1
int f = a++ + b-- * ++c - --d / e++;
System.out.println(a); // 3
System.out.println(b); // 1
System.out.println(c); // 2
System.out.println(d); // 0
System.out.println(e); // 2
System.out.println(f); // 6
}
}
- Note that the calculation results are different when ++ is written before and after:
++n means adding 1 first and then referencing n; calculating first, then assigning
n++ means citing n first and then adding 1; assigning first, and then
calculating It is easy to confuse yourself by mixing it into routine calculations.
Note:
Likes, comments, and reprints are welcome. Please give the link to the original text in an obvious place on the article page
. Those who know, thank you for reading my article in the vast crowd.
Where is the signature without personality!
For details, please follow me
and continue to update
| © 2021 03 - Guyu.com | 【Copyright All Infringement Must Be Prosecuted】 |