How to append a new array in php array

In PHP, array is a very common and important data type. When using arrays, we usually need to continuously add new elements to the array to meet our needs. So, in PHP, how to append a new array to an existing array?

1. Use the array_merge function to merge arrays

The array_merge function is a very convenient array merging function provided by PHP. It accepts multiple arrays as parameters and returns a new array containing all the elements in the original array.

You can add elements in the new array to an existing array by passing the existing array and the new array to be added as parameters to the array_merge function.

For example, we already have an array $a, and we want to append a new array $b to it:

$a = array('a', 'b', 'c');
$b = array('d', 'e', 'f');

Add the elements in the new array $b to the existing array$ through the array_merge function In a:

$c = array_merge($a, $b);

At this time, array $c contains all the elements in array $a and array $b.

It should be noted that when using the array_merge function to merge arrays, if a key name already exists in the original array and the key name is also present in the new array, then the value in the new array will overwrite the key name in the original array. value.

2. Use the " " operator to merge arrays

In addition to the array_merge function, you can also use the " " operator to merge two arrays. This method is simpler and more direct than using the array_merge function.

For example, we already have an array $a, and we want to append a new array $b to it:

$a = array('a', 'b', 'c');
$b = array('d', 'e', 'f');

Add the elements in the new array $b to the existing array through the " " operator In array $a:

$c = $a + $b;

At this time, array $c contains all the elements in array $a and array $b. It should be noted that when using the " " operator to merge arrays, if a key name already exists in the original array and the key name also exists in the new array, the value in the original array will be retained.

3. Use the array_push function to append elements

Another way to add elements to an array is to use the array_push function. This function adds one or more values ​​to the end of the original array and returns the length of the array after adding the new elements.

For example, append a new element to the end of the existing array $a:

$a = array('a', 'b', 'c');
array_push($a, 'd');

At this time, the original array $a becomes:

array('a', 'b', 'c', 'd');

It should be noted that, When using the array_push function to append elements to an array, you can only add elements to the end of the array and cannot specify other locations to add to the array.

4. Use the [] method to append elements

After PHP 5.4, a way to append elements to an array has been added, which is to use the [] method, which can be more concise and clear:

For example, append a new element to the end of the existing array $a:

$a = array('a', 'b', 'c');
$a[] = 'd';

At this time, the original array $a becomes:

array('a', 'b', 'c', 'd');

It should be noted that the [] method is used to When appending elements to an array, you can only add them to the end of the array, and cannot specify other locations to add to the array.

Summary:

Through the above method, you can easily append a new array or element to an existing array. When using the array_merge function or the " " operator to merge arrays, you need to pay attention to the overwriting of values ​​caused by duplicate key names. When using the array_push function or the [] method to append elements to an array, you need to note that you can only add to the end of the array. Just choose the appropriate method according to actual needs.

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