How to customize a one-dimensional array of key subscripts in php

In PHP, an array is a very useful and widely used data structure that can store data in a collection similar to a list or dictionary. By default, the key subscripts of one-dimensional arrays in PHP are automatically assigned, starting from 0 and increasing in sequence. However, sometimes we need to customize the key subscript of the array. In this case, we can use PHP's built-in functions or manually write code to achieve this.

This article mainly introduces the one-dimensional array of custom key subscripts. The main content includes the following aspects:

1. Use the array_combine function to create a one-dimensional array of custom key subscripts
2. Use a foreach loop to traverse the one-dimensional array of custom key subscripts
3. Manually write code to create a one-dimensional array of custom key subscripts
4. Use the array_combine function to create a custom key subscript One-dimensional array

array_combine function is a function in PHP that creates a new array with the value of one array as the key and the value of the other array as the value.

The syntax is as follows:

array_combine(array $keys, array $values): array

Among them, the $keys parameter is the key of the custom array, and the $values ​​parameter is the value of the custom array. Returns a new array with the values ​​in the $keys array as keys and the values ​​in the $values ​​array as values ​​inserted into the new array.

For example, we can use the array_combine function to create a one-dimensional array with strings as key subscripts. The code is as follows:

<?php

// 创建一个自定义键下标的一维数组
$keys = array("name", "age", "gender");
$values = array("Tom", 22, "male");
$custom_array = array_combine($keys, $values);

// 输出数组
print_r($custom_array);

?>

The output of the above code is:

Array
(
    [name] => Tom
    [age] => 22
    [gender] => male
)

As you can see, we used the array_combine function to successfully create a one-dimensional array with strings as key subscripts.

2. Use a foreach loop to traverse the one-dimensional array of custom key subscripts

After creating the one-dimensional array of custom key subscripts, we need to iterate through it and stored in the program. You can use a foreach loop to traverse an array.

The syntax is as follows:

foreach (array_expression as $key => $value) {
    statement(s);
}

Among them, the $value parameter represents the value of the element currently traversed in the array, and the $key parameter represents the key corresponding to the element currently traversed. $key and $value can be named whatever you want, but most developers will keep these two common names to better describe their meaning.

For example, we can use a foreach loop to traverse the one-dimensional array of custom key subscripts created above. The code is as follows:

<?php

// 创建一个自定义键下标的一维数组
$keys = array("name", "age", "gender");
$values = array("Tom", 22, "male");
$custom_array = array_combine($keys, $values);

// 遍历数组
foreach ($custom_array as $key => $value) {
    echo $key . ": " . $value . "
";
}

?>

The output result of the above code is:

name: Tom
age: 22
gender: male

As you can see, we used the foreach loop to successfully traverse the one-dimensional array of custom key subscripts and output the key and value of each element to the screen.

3. Manually write code to create a one-dimensional array of custom key subscripts

In addition to using PHP's built-in functions, we can also manually write code to create a custom key subscript The target one-dimensional array. The key subscript of an array in PHP can not only be a number, string and other data types, but also a scalar value, object or an array.

For example, we can use the following code to manually create a one-dimensional array of custom key subscripts:

<?php

// 创建一个自定义键下标的一维数组
$custom_array = array(
    "name" => "Tom",
    "age" => 22,
    "gender" => "male"
);

// 遍历数组
foreach ($custom_array as $key => $value) {
    echo $key . ": " . $value . "
";
}

?>

The above code can also successfully implement a one-dimensional array of custom key subscripts and use a foreach loop Traverse and output the elements in the array.

Summary

This article mainly introduces how to create a one-dimensional array of custom key subscripts in PHP, and uses PHP built-in functions and manual coding methods. Since arrays are a very common data structure in PHP, mastering the method of customizing key subscripts is very helpful for better development of PHP applications.

The above is the detailed content of How to customize a one-dimensional array of key subscripts in php. For more information, please follow other related articles on the PHP Chinese website!