Analyzing PHP Array Deep Copy Methods: Comparison of Efficiency, Complexity and Applicability

PHP methods for deep copying arrays are: shallow copy (clone): efficient, but only copies the top elements. Deep copy (array_map(clone, $array)): clone each element, recursive method, less efficient. JSON serialization/deserialization: Creates deep copies, but is inefficient and consumes memory. Recursive function: flexible and efficient, but requires a large amount of code for complex arrays. Third-party library (DeepCopy): Complex and efficient solution for general use.

Analysis of PHP array deep copy method: comparison of efficiency, complexity and applicability

Introduction

Array deep copying in PHP is essential for working with and modifying array data without affecting the original array. This article will explore the commonly used deep copy methods in PHP, analyzing their efficiency, complexity, and applicability in different situations.

Method

1. Shallow copy: clone keyword

clone keyword only creates A shallow copy of the original array, meaning it copies the topmost elements of the array, but the nested array or object still references the values ​​in the original array.

2. Deep copy: array_map(clone, $array)

This method applies the clone keyword to each element in the array, thus Create a deep copy of each element. However, it uses a recursive approach, which can be inefficient for arrays with a large number of nested elements.

3. JSON serialization/deserialization

This method converts the array into a JSON string, then uses json_encode() andjson_decode() function converts it back to an array. Although it creates a deep copy, it is less efficient than other methods and creates unnecessary memory consumption.

4. Recursive functions

You can use recursive functions to deeply copy an array, manually traverse the array and create a new copy of the array. This approach is flexible and efficient, but can require a lot of code for complex arrays.

5. Third-party libraries (such as DeepCopy)

You can use third-party libraries to handle deep copying, providing more complex and efficient solutions. One of the popular libraries is DeepCopy.

Practical case

Suppose we have a multidimensional array containing nested arrays:

$original = [
  'name' => 'John Doe',
  'address' => [
    'street' => 'Main Street',
    'city' => 'New York'
  ]
];

Test results

We tested the efficiency and accuracy of different methods using the following code:

$start = microtime(true);
$copy = array_map('clone', $original);
$end = microtime(true);
$time = $end - $start;
echo "array_map(clone): $time seconds\n";

Similarly, we can test other methods.

Comparative analysis

HighLowShallow copy MediumHighLots of nested elementsJSON ConversionLowLowSmall Simple ArrayRecursive Function高高Complex arraythird-party library高mediumGeneral purpose

Method	Efficiency	Complexity	Applicability
##clone
array_map(clone)

Conclusion

There are many ways to deep copy PHP arrays, each method has Its advantages and disadvantages. For performance-critical and less nested arrays, it is recommended to use the

clone or DeepCopy libraries. For more complex arrays, recursive functions are more flexible. As for JSON conversion, it's only suitable for small, simple arrays that don't require high efficiency.

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