In PHP programming, the data type of array is often used. Determining whether an element is in an array is a very common operation. This article will introduce a variety of methods to determine whether elements are in an array, hoping to be helpful to PHP beginners.
1. Use the in_array function
The in_array function is a way to quickly determine whether an element is in an array. The function prototype is:
bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )
where $needle is the element to be found and $haystack is the target Array, $strict is whether to enable type checking. The default is FALSE, which means no type checking.
The following is an example:
$arr = array("apple", "banana", "orange"); if (in_array("banana", $arr)) { echo "找到了!"; } else { echo "没找到。"; }
The output result is: Found!
2. Use the array_search function
The array_search function is also a function used to find whether an element is in an array. However, it returns the key name of the element rather than a Boolean value. The function prototype is:
mixed array_search ( mixed $needle , array $haystack [, bool $strict = FALSE ] )
where $needle is the element to be found and $haystack is the target Array, $strict is whether to enable type checking. The default is FALSE, which means no type checking.
The following is an example:
$arr = array("apple", "banana", "orange"); $key = array_search("banana", $arr); if ($key !== false) { echo "找到了!键名是:" . $key; } else { echo "没找到。"; }
The output result is: Found! The key name is: 1
3. Use isset function
isset function is a built-in function in PHP, used to detect whether the variable is set and non-NULL. We can use the isset function and the key name of the array to determine whether an element is in the array. Sample code:
$arr = array("apple", "banana", "orange"); if (isset($arr[1])) { echo "找到了!"; } else { echo "没找到。"; }
The output result is: Found!
4. Use the array_key_exists function
The array_key_exists function is a function that checks whether the specified key name exists in the array. The function prototype is:
bool array_key_exists (mixed $key, array $array)
Among them, $key is the key name to be found, and $array is the target array.
Sample code:
$arr = array("apple", "banana", "orange"); if (array_key_exists(1, $arr)) { echo "找到了!"; } else { echo "没找到。"; }
The output result is: Found!
5. Use the indexOf function
The indexOf function is a custom function used to check whether the element is in the array. The function prototype is:
function indexOf($array, $search_value)
{
foreach($array as $key => $value) { if($value === $search_value) { return $key; } } return false;
}
Among them, $array is the target array and $search_value is the target array. The element to find.
Sample code:
$arr = array("apple", "banana", "orange"); $key = indexOf($arr, "banana"); if ($key !== false) { echo "找到了!键名是:" . $key; } else { echo "没找到。"; }
The output result is: Found! The key name is: 1
The above are several methods in PHP to determine whether an element is in an array, among which in_array and array_search are the most commonly used methods. In actual use, you can choose according to your own needs.
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