php modifies a set of arrays

In PHP, modifying arrays is a very common operation, because arrays are a very common data type. The value of the array can be modified, that is to say, using PHP language, we can add, delete, modify and other operations on the elements in the array.

This article will introduce how to modify an array in PHP. As we will see, modifying an array in PHP is a very simple operation, we only need to use some simple functions and syntax rules.

1. Modify array elements

There are three ways to modify array elements in PHP:

1. Use subscripts to modify the value of the element
   Each element in the array Each element has a unique subscript, and we can access and modify the elements in the array through the subscript. The following is an example:

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

Output result:

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

We can see that the value of $array[1] has been modified from the original 2 to 4.

2. Use the array_splice() function
   array_splice() The function can insert or delete elements in the array and return the modified array. We can modify elements in an array by specifying the position of insertion or deletion and the number of elements. The following is an example:

$array = array(1, 2, 3);
array_splice($array, 1, 1, array(4));
print_r($array);

Output result:

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

We can see, array_splice($array, 1, 1, array(4)) The second element (subscript 1) of the $array array is deleted, and an element is inserted at this position. The inserted element is an array with only one element with a value of 4.

3. Directly assign values ​​to the array
   Another method is to directly assign values ​​to the array, for example:

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

Output result:

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

We can see that directly assigning the array $array to array(1, 4, 3) modifies the value of the array.

2. Modify the key name of the element

In PHP, we can also modify the key name of the array element. The following is an example:

$array = array("a" => 1, "b" => 2, "c" => 3);
$array["d"] = $array["b"];
unset($array["b"]);
print_r($array);

Output result:

Array(
    [a] => 1
    [c] => 3
    [d] => 2
)

We can see that first the value of the element with the key name "b" is assigned to the element with the key name "d" , and use the unset() function to delete the element with the key name "b" from the array.

3. Modify multi-dimensional arrays

In PHP, we can also modify the elements in multi-dimensional arrays. The following is an example:

$array = array(
    array("id" => 1, "name" => "John"),
    array("id" => 2, "name" => "Amy"),
    array("id" => 3, "name" => "Tom")
);

$array[1]["name"] = "Andy";

print_r($array);

Output result:

Array(
    [0] => Array(
        [id] => 1
        [name] => John
    )
    [1] => Array(
        [id] => 2
        [name] => Andy
    )
    [2] => Array(
        [id] => 3
        [name] => Tom
    )
)

We can see that by using the array subscript and key name, we can easily modify the value of this multi-dimensional array.

Summary

In PHP, the operation of modifying arrays is very common. We can use subscripts, the array_splice() function, or directly assign values ​​to the array to modify the elements in the array. If we want to modify the key name of an array element, we can use the key name to access and modify the elements in the array. Of course, in multi-dimensional arrays, we can also use similar methods to modify the elements in the array.

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