Introduction to how to use PHP array_search() function

In PHP, an array is a very useful data type that can store multiple values ​​and access each value through an index. PHP provides many functions for processing arrays, among which the array_search() function is one of them. This article will introduce how to use the PHP array_search() function.

1. Basic usage of array_search() function

array_search() function is used to search for a given value in an array and return the key of the value. The syntax is as follows:

array_search($value, $array, $strict = false)

Among them, $value is the value to be searched, $array is the array to be searched, $strict is an optional parameter, and the default is false, indicating whether to compare types and values ​​when searching.

The following is a simple example that demonstrates how to use the array_search() function to find values ​​in an array:

$fruits = array('apple', 'banana', 'cherry', 'orange');
$key = array_search('cherry', $fruits);
echo $key; // 输出 2

In the above example, we define an array $fruits, and Use the array_search() function to find elements with the value 'cherry'. The function returns the key of the element, which is 2.

2. Search using strict mode

By default, the array_search() function does not distinguish between types and values ​​when searching. However, strict mode can be enabled by setting the $strict parameter to true. This means that during the search, both types and values ​​are compared. The following is an example of searching an array using strict mode:

$numbers = array(10, '20', 30, '40');
$key = array_search('20', $numbers, true);
echo $key; // 输出空

In the above example, we have defined an array $numbers which contains some values ​​of numeric and string types. We then use the array_search() function to search the array for an element with value '20' and set the $strict parameter to true. Because both types and values ​​are compared during the search, a null value is returned.

3. Searching in multidimensional arrays

array_search() function can search for values ​​in multidimensional arrays. However, the search only searches in the first dimension and does not continue to search deeper dimensions. The following is an example of how to search for values ​​in a multidimensional array:

$students = array(
  array('name' => 'Alice', 'age' => 20),
  array('name' => 'Bob', 'age' => 25),
  array('name' => 'Charlie', 'age' => 30),
  array('name' => 'David', 'age' => 35)
);

$key = array_search(25, array_column($students, 'age'));
echo $key; // 输出 1

In the above example, we defined a multidimensional array named $students, which contains several student information. We then use the array_column() function to get the student's age from $students and then use the array_search() function to find the element with the value 25. Since you are searching a one-dimensional array, the function returns the key of the element, which is 1.

4. Search for values ​​after the specified position

array_search() function also accepts the third parameter $offset, which is used to specify the position where the search starts. Here is an example of searching for a value after a specific value in an array:

$numbers = array(10, 20, 30, 40, 50, 60);
$key = array_search(40, $numbers, true);
$offset = $key + 1;
$next_key = array_search(50, $numbers, false, $offset);
echo $next_key; // 输出 4

In the above example, we have defined an array named $numbers and are looking for the key of the element with value 40 in that array . We then use the $offset variable to set the search start position to the position next to the element with a value of 40. Finally, we use the array_search() function to search the array for an element with value 50 and return the key of that element. Since the search starts at position 4, the key returned by the function is 4.

Summary:

This article introduces how to use the PHP array_search() function, including basic usage, strict mode search, searching in multi-dimensional arrays, searching for values ​​after specified positions, etc. Mastering these contents is very important for PHP developers, I hope this article can be helpful to you.

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