Add elements to array in php

In PHP programming, arrays are a very commonly used data type. The characteristic of an array is that it can store a set of data and access this data through index or key value. When writing PHP code, we often need to add new elements to an array. This article will introduce how to add elements to an array in PHP.

1. Add elements to the end of the array

First, let’s introduce how to add new elements to the end of the array. You can use the PHP built-in function array_push() to add one or more elements to the end of an array.

The syntax is as follows:

array_push($array, $value1, $value2, ...)

Among them, $array represents the target array to add elements, $value1 , $value2, ...indicates the specific element to be added. This function adds a new element to the end of the target array and returns the length of the new array.

Code example:

$arr = array(1, 2, 3);
$len = array_push($arr, 4, 5);
print_r($arr);
echo "新数组长度为：$len";

The output result is:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)
新数组长度为：5

2. Add elements to the head of the array

In addition to adding elements to the tail of the array, there are Sometimes we also need to add elements to the head of the array. This operation can be accomplished using the PHP built-in function array_unshift().

The syntax is as follows:

array_unshift($array, $value1, $value2, ...)

Among them, $array represents the target array to which elements are to be added, $value1 , $value2, ...indicates the specific element to be added. This function adds a new element to the head of the target array and returns the length of the new array.

Code example:

$arr = array(1, 2, 3);
$len = array_unshift($arr, 0);
print_r($arr);
echo "新数组长度为：$len";

The output result is:

Array
(
    [0] => 0
    [1] => 1
    [2] => 2
    [3] => 3
)
新数组长度为：4

3. Add elements to the specified position

Sometimes we need to add elements to the specified position in the array Add elements. This operation can be accomplished using the PHP built-in function array_splice().

The syntax is as follows:

array_splice($array, $offset, $length, $replacement)

Among them, $array represents the target array to be operated on, and $offset represents the target array to be operated on. The position of adding elements, $length indicates the number of elements to be deleted, and $replacement indicates the elements to be added to the array.

In this function, the two parameters $length and $replacement are optional. If you do not need to delete elements, the $length parameter can be omitted; if you only need to add elements, the $length parameter can be set to 0.

If there are multiple elements to be added, they can be passed in an array. For example:

$arr = array("apple", "banana", "cherry");
array_splice($arr, 1, 0, array("orange", "grape"));
print_r($arr);

The output result is:

Array
(
    [0] => apple
    [1] => orange
    [2] => grape
    [3] => banana
    [4] => cherry
)

In the above code, we added two elements "orange" and "grape" at the position where $offset is 1.

4. Use assignment statements to add elements

The above three methods all use PHP’s own functions to add elements. In addition, we can also use PHP's assignment statement to add elements directly. This method is relatively simple, but not very flexible and is only suitable for adding elements to the end of the array.

Code example:

$arr = array(1, 2, 3);
$arr[] = 4;
print_r($arr);

The output result is:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
)

In the above code, we use a statement like $arr[] = 4 to add to the end of the array A new element4.

Summary

This article introduces several methods of adding elements to an array in PHP, including array_push(), array_unshift(), array_splice() and using assignment statements to add elements. In actual development, we can choose which method to use based on specific needs.

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