The difference between i++ and ++i in java

The difference between i and i in Java: the order of operations: i first obtains the value and then increments; i first increments and then obtains the value. Return value: i returns the value before auto-increment; i returns the value after auto-increment. Usage scenarios: When avoiding side effects or controlling the order of evaluation of conditional statements, you need to pay attention to the difference between the two.

The difference between i and i in Java

In Java, i and i are both increment operators , but the way they operate on variables is slightly different.

i (post-increment)

The post-increment operator i will first obtain the current value of i, and then increase the value of i by 1.

<code class="java">int i = 10;
int result = i++; // result = 10
System.out.println(i); // 输出 11</code>

i (prefixed increment)

The prefixed increment operator i will first increase the value of i by 1, and then obtain the value of i.

<code class="java">int i = 10;
int result = ++i; // result = 11
System.out.println(i); // 输出 11</code>

Difference

Return value:

• i Returns the original value and then increments it.
• i returns the new value after incrementing.

Evaluation order:

• i The expression is evaluated first, then incremented.
• i is incremented first, then the expression is evaluated.

Usage scenarios:

In most cases, using i and i won't make much of a difference. However, in some cases it is important to understand the difference between them, for example:

• Avoid side effects: If there are multiple increment operators in an expression, Using i ensures that the increment operation occurs after the expression is evaluated, thus avoiding unexpected side effects.
• Conditional statements: If i is used in a conditional statement, the original value will be used to evaluate the condition before it is incremented. Instead, i will be incremented first and then the condition will be evaluated.

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