php-loops

PHP Loops — Which is faster?

These are my notes about PHP loops, which are faster, and so on.

I just compared it in one way and wrote the test results. It is important what do yo do inside the looping.

Note: echo is affecting testing performance. But it is ok for getting an idea that what happens when loops are working.

Using reference in foreach

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Summary

• It seems faster to not use references. When I get this result firstly I was surprised. The Zend Engine, PHP’s core, uses a copy-on-write optimization mechanism that does not create a copy of a variable until it is modified. Passing by reference usually breaks the copy-on-write pattern and requires a copy whether you modify the value or not.
• Also using reference is dangerous in this case because after the foreach if you forgot to unset $v it can cause unwanted results.
• So, in PHP 7+ pass-by-value is faster than pass-by-reference.
• foreach($array as $item) will leave the variable $item untouched after the loop. If the variable is a reference, foreach($array as &$item)it will "point" to the last element of the array even after the loop.

Is for loop faster than foreach?

• With your usage or need, it can be changed actually. For this example we can say for is faster than foreach.
• In most cases, foreach is more readable than for.

What is the fastest loop?