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Is there a difference in ++i and i++ in a for loop? for循环中的++i和i++有区别吗？ Is it simply a syntax thing? 这仅仅是语法问题吗？

#1楼

参考：

#2楼

They both increment the number. 它们都增加数字。 ++i is equivalent to i = i + 1 . ++i等于i = i + 1 。

i++ and ++i are very similar but not exactly the same. i++和++i非常相似，但不完全相同。 Both increment the number, but ++i increments the number before the current expression is evaluated, whereas i++ increments the number after the expression is evaluated. 两者都增加数字，但是++i增加对当前表达式求值之前的数字，而i++增加对表达式求值之后的数字。

int i = 3;int a = i++; // a = 3, i = 4int b = ++a; // b = 4, a =

Check . 检查 。

#3楼

There is no difference if you are not using the value after increment in the loop. 如果在循环中不使用增量后的值，则没有区别。

for (int i = 0; i < 4; ++i){cout<

Both the loops will print 0123. 这两个循环都将打印0123。

But the difference comes when you uses the value after increment/decrement in your loop as below: 但是，当您在循环中使用递增/递减后的值时，会出现如下差异：

Pre Increment Loop: 预增量循环：

for (int i = 0,k=0; i < 4; k=++i){cout<<<" ";       cout<
    
     <<" "; }
    

Output: 0 0 1 1 2 2 3 3 输出：0 0 1 1 2 2 3 3

Post Increment Loop: 后增量循环：

for (int i = 0, k=0; i < 4; k=i++){cout<<<" ";       cout<
    
     <<" "; }
    

Output: 0 0 1 0 2 1 3 2 输出：0 0 1 0 2 1 3 2

I hope the difference is clear by comparing the output. 我希望通过比较输出来清楚区别。 Point to note here is the increment/decrement is always performed at the end of the for loop and hence the results can be explained. 这里要注意的是，增量/减量始终在for循环的末尾执行，因此可以解释结果。

#4楼

I dont know for the other languages but in Java ++i is a prefix increment which means: increase i by 1 and then use the new value of i in the expression in which i resides, and i++ is a postfix increment which means the following: use the current value of i in the expression and then increase it by 1. Example: 我不知道其他语言，但是在Java ++中，i是前缀增量 ，这意味着：将i加1，然后在i所驻留的表达式中使用i的新值，并且i ++是后缀增量 ，这意味着：在表达式中使用i的当前值，然后将其增加1。示例：

public static void main(String [] args){    int a = 3;    int b = 5;    System.out.println(++a);    System.out.println(b++);    System.out.println(b);

} and the output is: 的输出是：

• 4 4
• 5 5
• 6 6

#5楼

The question is: 问题是：

Is there a difference in ++i and i++ in a for loop? for循环中的++ i和i ++有区别吗？

The answer is: No . 答案是： 不 。

Why does each and every other answer have to go into detailed explanations about pre and post incrementing when this is not even asked? 为什么甚至在没有问到的情况下，每个其他答案都必须对前后递增进行详细说明？

This for-loop: 这个for循环：

for (int i = 0; // Initialization     i < 5;     // Condition     i++)       // Increment{   Output(i);}

Would translate to this code without using loops: 无需使用循环即可转换为以下代码：

int i = 0; // InitializationloopStart:if (i < 5) // Condition{   Output(i);   i++ or ++i; // Increment   goto loopStart;}

Now does it matter if you put i++ or ++i as increment here? 现在，将i++或++i作为增量在这里有关系吗？ No it does not as the return value of the increment operation is insignificant. 不可以，因为增量操作的返回值无关紧要。 i will be incremented AFTER the code's execution that is inside the for loop body. 在for循环体内执行代码后， i将递增。

#6楼

It boggles my mind why so may people write the increment expression in for-loop as i++. 这让我感到困惑，为什么人们可能会像i ++一样在for循环中编写增量表达式。

In a for-loop, when the 3rd component is a simple increment statement, as in 在for循环中，当第三个组件是一个简单的增量语句时，如

for (i=0; i

or 要么

for (i=0; i

there is no difference in the resulting executions. 执行的结果没有差异。

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