There are three ways to check whether the value exists in PHP array: use in_array() for one-dimensional arrays, such as in_array('banana', $array); use array_search() for key names, such as array_search('Alice', $array); use multi-dimensional arrays, for custom recursive function in_multi_array(). Note that in_array() does not strictly match the type by default. You can add the third parameter true for strict checking, while array_search() results should be judged using !== false to avoid misjudgment.
The most straightforward way to check if a value exists in a PHP array is to use the built-in function in_array() . It accepts two required parameters: the value to be found and the target array, returning a boolean value indicating whether it exists.
Use the in_array() function to determine whether the value exists
This is the most common and easiest way. For example:
$array = ['apple', 'banana', 'orange'];
if (in_array('banana', $array)) {
echo 'existence';
} else {
echo 'not exists';
} The above example outputs "existence" because 'banana' is indeed in the array.
Note: By default,
in_array()does not perform type checking. If you want to strictly match (for example, it is considered equal only when the values ??and types are the same), you can pass in the third parametertrue:in_array('123', [123], true); // Return false because one is a string and the other is an integer
Want to get the key name? Use array_search()
If you want to know not only whether a value exists, but also find its key name in the array, you can use array_search() :
$array = ['name' => 'Alice', 'age' => 30];
$key = array_search('Alice', $array);
if ($key !== false) {
echo "The value exists in the key '$key'";
} This function returns the key of the match, and if not found, it returns false . Note that you should use !== false to determine the result, otherwise you may misjudge keys such as 0 or '0' .
How to check multi-dimensional arrays?
If you are facing a multi-dimensional array, you cannot use in_array() directly. You have to write a loop or recursive function yourself. For example:
function in_multi_array($value, $array) {
foreach ($array as $element) {
if (is_array($element)) {
if (in_multi_array($value, $element)) {
return true;
}
} elseif ($element === $value) {
return true;
}
}
return false;
}This will allow the data of the nested structure to be processed. But pay attention to performance issues, especially when the array is very large.
To summarize the method:
- Normal one-dimensional array →
in_array() - To find the key name →
array_search() - Multidimensional array → Custom recursive functions or traversal search
Basically, just choose the appropriate method according to the actual structure.
The above is the detailed content of How to check if value exists in php array?. For more information, please follow other related articles on the PHP Chinese website!
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