How to change one-dimensional array in php

One-dimensional array is a very basic data structure in PHP. It is composed of one or more elements, each element corresponds to a key and a value. In PHP, you can use some built-in functions to add, delete, modify and traverse one-dimensional arrays.

So, how to modify a one-dimensional array in PHP? Several commonly used methods will be introduced below.

1. Use key names to modify

Each element of a one-dimensional array has a key and a value, and you can use the key name to modify the corresponding value.

Example:

$arr = array('name' => 'Tom', 'age' => 20);

// 修改 name 的值
$arr['name'] = 'Jerry';

In the above example, we can see that the value corresponding to name is obtained through $arr['name'], and then it is Assign the new value Jerry.

2. Using the array_splice() function

This function is a standard function in PHP and can be used to delete, replace or add elements in an array. If we only need to modify an element in a one-dimensional array, we can do it through array_splice(). Specific examples are as follows:

Example:

$arr = array('a','b','c','d','e');

// 将 $arr 中第 3 个元素替换为 h
array_splice($arr, 2, 1, 'h');

In the above example, the first parameter of the array_splice() function $arr is to The array of operations, the second parameter 2 is the position of the element to be adjusted, 1 is the number of elements to be replaced, and the last parameter is the new element to be inserted. When this function completes, the $arr array will become array('a','b','h','d','e').

3. Use the array_replace() function

This function is a powerful one-dimensional array modification function in PHP. Use it to easily replace values ​​in a one-dimensional array.

Example:

$arr = array('name' => 'Tom', 'age' => 20, 'gender'=> 'male');

// 将 $arr 中 age 的值改为 30
$arr = array_replace($arr, array('age' => 30));

In the above example, the first parameter $arr in the array_replace() function is to be modified One-dimensional array, the second parameter is also an array, containing the key-value pairs that need to be updated. When the function completes, the $arr array will become array('name' => 'Tom', 'age' => 30, 'gender'=> 'male') ;.

4. Use the array_map() function

This function is a basic function in PHP that can modify the value of the array according to the specified callback function. It should be noted that the array_map() function will save the modified result in a new array, and the original array will not be modified.

Example:

$arr = array('apple', 'banana', 'orange');

// 将 $arr 中 apple 和 banana 替换为 peach 和 kiwi
$new_arr = array_map(function($value) {
    if ($value == 'apple') {
        return 'peach';
    } else if ($value == 'banana') {
        return 'kiwi';
    } else {
        return $value;
    }
}, $arr);

In the above example, the first parameter of the array_map() function is a callback function used to modify the elements in the array. The second parameter is an array, that is, the original array to be modified. When the function completes, the $new_arr array will become array('peach', 'kiwi', 'orange').

To sum up, the above introduces several commonly used methods of modifying one-dimensional arrays in PHP. Which method to use needs to be chosen on a case-by-case basis. In PHP, array is a very important data type, and it is very important to master its basic usage.

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