How to get the position of a value in an array in php

In PHP, array is a very useful data type. It allows us to save multiple values ​​together and access these values ​​by index or key. Sometimes we may want to know the position of a certain value in the array. In this case, we need to use the array search function.

In PHP, we can use various methods to find values ​​in an array. Several of these methods will be introduced below.

1. Use the array_search function

The array_search function allows us to find a specific value in an array and return the key name of the first occurrence of the value. If the value does not exist, returns false.

Example:

$arr = array('a', 'b', 'c', 'd');

$key = array_search('b', $arr);

echo $key; // 输出 1

In the above example, we use the array_search function to find the value 'b' in the array $arr and return the key name 1 of the value.

2. Use the array_keys function

The array_keys function can return the key names of all elements in the array with the specified value. If the value does not exist, an empty array is returned.

Example:

$arr = array('a', 'b', 'c', 'd', 'b');

$keys = array_keys($arr, 'b');

print_r($keys); // 输出 Array ( [0] => 1 [1] => 4 )

In the above example, we use the array_keys function to find all elements with a value of 'b' in the array $arr and return their key names.

3. Use the array_values ​​function

The array_values ​​function returns all the values ​​in the array, excluding the key names.

Example:

$arr = array('a', 'b', 'c', 'd');

$values = array_values($arr);

print_r($values); // 输出 Array ( [0] => a [1] => b [2] => c [3] => d )

In the above example, we use the array_values ​​function to return all the values ​​in the array $arr.

4. Use the in_array function

The in_array function is used to find whether a certain value exists in the array. Returns true if present, false otherwise.

Example:

$arr = array('a', 'b', 'c', 'd');

$is_in = in_array('b', $arr);

echo $is_in; // 输出 1

In the above example, we use the in_array function to find whether the value 'b' exists in the array $arr, and it returns true.

Summary:

In PHP, the array search function is very powerful, and we can find specific values ​​in a variety of ways. In actual development, we should choose the appropriate method according to specific scenarios in order to improve the efficiency and readability of the code.

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