PHP array deep copy method showdown: speed, memory usage and reliability

Comparison of PHP deep copy methods: Speed: clone is the fastest, followed by json_encode() json_decode(). Memory usage: json_encode() json_decode() is the least, serialize() unserialize() is the most. Reliability: All methods ensure that the original array is not affected by modifications to the copy.

PHP array deep copy method showdown: speed, memory usage and reliability

Introduction
Deep copying is crucial when dealing with multi-dimensional arrays in PHP. It creates a true copy of the array and is useful when you need to modify elements in the copy without affecting the original array. This article will compare four popular PHP deep copy methods:

Method

• ##clone
• array_map(clone, $array)
• serialize() unserialize()
• json_encode() json_decode()

Practical caseFor comparison, we create a multi-dimensional array containing 1,000 elements:

$array = range(1, 1000);
$array[] = ['a', 'b', 'c'];
$array[] = ['x' => 1, 'y' => 2];

Speed ​​testUse
microtime() to time the execution time of each method:

$time = microtime(true);
$cloneCopy = clone $array;
$microtime = microtime(true) - $time;

$time = microtime(true);
$arrayMapCloneCopy = array_map(clone, $array);
$microtime2 = microtime(true) - $time;

$time = microtime(true);
$serializeCloneCopy = unserialize(serialize($array));
$microtime3 = microtime(true) - $time;

$time = microtime(true);
$jsonCloneCopy = json_decode(json_encode($array), true);
$microtime4 = microtime(true) - $time;

Result:

Method Time (seconds)##clonearray_map(clone, $array)serialize() unserialize()##json_encode() json_decode()##Memory usage testUse

##8.9e-6
2.1e-5
8.1e-5
4.7e-5

memory_get_usage()

Measure the memory usage of each method:

$memory = memory_get_usage();
$cloneCopy = clone $array;
$memory2 = memory_get_usage() - $memory;

$memory = memory_get_usage();
$arrayMapCloneCopy = array_map(clone, $array);
$memory3 = memory_get_usage() - $memory;

$memory = memory_get_usage();
$serializeCloneCopy = unserialize(serialize($array));
$memory4 = memory_get_usage() - $memory;

$memory = memory_get_usage();
$jsonCloneCopy = json_decode(json_encode($array), true);
$memory5 = memory_get_usage() - $memory;

Result:

Method

Memory usage (bytes)##clone56,000##88,000##112,000Reliability testing

	array_map(clone, $array)
	serialize() unserialize()
##json_encode() json_decode()	64,000
	Reliability testing ensures that the original array remains unchanged when the copy is modified : $cloneCopy[0] = 100; $arrayMapCloneCopy[0] = 100; $serializeCloneCopy[0] = 100; $jsonCloneCopy[0] = 100; echo $array[0]; // 输出：1 assert($array[0] == 1);

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