How to change the value in an array in php

PHP is a powerful programming language that provides many methods for operating arrays. Array is a very practical data structure that can be used to store a group of related data, such as a product list or a student list. When using an array, we may need to modify some of its values. This article will introduce several ways to modify the values ​​in PHP arrays.

1. Use array subscripts to assign values

Arrays in PHP can use subscripts to access and modify their values. The subscript starts from 0 and can be of any type (integer, floating point number, string, etc.). We can modify the corresponding value by assigning a value to the array subscript. Here is an example:

$fruits = array('apple', 'banana', 'orange');
$fruits[1] = 'pear';
print_r($fruits);

Output:

Array
(
    [0] => apple
    [1] => pear
    [2] => orange
)

In the above example, we modified the value at index 1 in the $fruits array to 'pear'. The output indicates that the element in the array has been successfully modified.

2. Use the array_splice() function

The array_splice() function can be used to delete one or more elements in the array and insert new elements at the deleted positions. This function is used as follows:

array_splice(array &$input, int $offset, int $length = 0, mixed $replacement = array()): array

Among them, the parameter $input specifies the array to be operated on; $offset specifies the starting position of deletion/insertion; $length specifies the number of elements to be deleted (the default is 0, that is No elements are deleted); $replacement specifies the element to be inserted. Below is an example that shows how to use the array_splice() function to replace the values ​​of certain elements in an array.

$names = array('Tom', 'Jerry', 'Spike', 'Tyke');
array_splice($names, 2, 1, 'Butch');
print_r($names);

Output:

Array
(
    [0] => Tom
    [1] => Jerry
    [2] => Butch
    [3] => Tyke
)

In the above example, we deleted the element with index 2 in the $names array and inserted a new element 'Butch' at that position.

3. Use foreach loop

The foreach loop can be used to traverse each element in the array and modify it. We can use the reference ampersand symbol in a loop to modify the value of an element. For example:

$grades = array('John' => 85, 'Mary' => 92, 'Bob' => 78);
foreach ($grades as &$value) {
    $value = $value + 5;
}
print_r($grades);

Output:

Array
(
    [John] => 90
    [Mary] => 97
    [Bob] => 83
)

In the above example, we used a foreach loop to traverse each element in the $grades array and modify it. Due to the use of the reference & symbol, we can directly modify the value of the corresponding element in the original array.

Summary

Through the above three methods, we can easily modify the element values ​​in the PHP array. Usually, the first method (assignment using array subscripts) is the most common and simple. Using the array_splice() function, you can delete elements and insert new elements into the array at the same time, which has a certain degree of flexibility. When we need to modify each element in the array, we can use a foreach loop and use the reference & symbol to directly modify the element value in the array. The selection of these methods requires judgment and selection based on specific usage scenarios and needs.

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