How to copy an array with php

In PHP, copying an array is one of the very common operations. Usually we can use some built-in functions to complete this operation. This article will introduce how to use PHP to copy an array.

Method 1: Use the assignment operator

Use the assignment operator "=" to assign the value of one array to another array. If we want to create a separate copy of the original array, we can use the following code:

$originalArray = array("apple", "banana", "cherry");
$newArray = $originalArray;

In the above code, the $newArray variable will contain all the values ​​of $originalArray. This operation is done by passing a copy of the reference of $originalArray to $newArray. This means that if we change a value in $originalArray, the corresponding value in $newArray will change accordingly. This is because they both refer to the same memory address. If we need a completely independent copy, we can use method two.

Method 2: Use the array_slice function

Method 2 uses the array_slice function to obtain a subset of an array to generate a new array. It can be achieved in the following way:

$originalArray = array("apple", "banana", "cherry");
$newArray = array_slice($originalArray, 0);

In this code, the second parameter of the array_slice function is the starting index, here we pass in 0 to intercept the entire array. The third parameter is the length of the interception. We have not set it here. The default value is the length of the array.

The above code will create a completely independent new array. If $originalArray is modified, $newArray will not be affected.

Method 3: Use the json_encode and json_decode functions

Method 3 creates a brand new array by encoding the original array into a JSON string and then decoding it:

$originalArray = array("apple", "banana", "cherry");
$newArray = json_decode(json_encode($originalArray));

In In this code, we use the json_encode function to convert $originalArray into a JSON string, and then use the json_decode function to decode it into a new array.

This method can create a new array because the decoding process is not done by reference. This also means that if a value in the original array is an object or array, it will also be copied.

In summary, the above are three common methods of copying arrays in PHP. We can use different methods according to specific needs. The assignment operator and the array_slice function both create a new array, while the json_encode and json_decode functions copy objects and arrays.

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