PHP中的++ $ i和$ i ++有什么区别?

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PHP中的++$i和$i++有什么区别?

What's the difference between ++$i and $i++ in PHP?

推荐答案

++$i是预递增的，而$i++是后递增的.

++$i is pre-increment whilst $i++ post-increment.

• 预递增:先递增变量i，然后取消引用.
• 后递增:取消引用，然后递增i

• pre-increment: increment variable i first and then de-reference.
• post-increment: de-reference and then increment i

利用PHP事实 允许您后递增($ i ++) 和预增量(++ $ i).含义 只要你不一样就一样 写类似$ j = $ i ++的东西， 但是预增量几乎是10％ 更快，这意味着您应该 从后增量切换到预增量 有机会的时候 特别是在严密的循环中 特别是如果您对 微观优化！" - TuxRadar

"Take advantage of the fact that PHP allows you to post-increment ($i++) and pre-increment (++$i). The meaning is the same as long as you are not writing anything like $j = $i++, however pre-incrementing is almost 10% faster, which means that you should switch from post- to pre-incrementing when you have the opportunity, especially in tight loops and especially if you're pedantic about micro-optimisations!" - TuxRadar

为进一步澄清，PHP中的后增量已被记录为存储一个临时变量，该临时变量归因于这10％的开销(相对于前增量).

For further clarification, post-incrementation in PHP has been documented as storing a temporary variable which attributes to this 10% overhead vs. pre-incrementation.