PHP method to determine whether a string exists in an array element_PHP tutorial

Method 1: Use in_array(value,array,type)

type optional. If this parameter is set to true, it is checked whether the type of the searched data and the value of the array are the same.

Copy code The code is as follows:

$arr = array('can','how','method',' know','no','don't');
//in_array(value,array,type)
$isin = in_array("how 2",$arr);
if($isin) {
echo "in====".$isin;
}else{
echo "out====".$isin;
}

Method 2:

array_key_exists 'array_key_exists() function determines whether the specified key exists in an array. If the key exists, it returns true, otherwise it returns false. array_key_exists(key,array

Method 3:

array_search() function is the same as in_array(), searching for a key value in the array. If the value is found, the key of the matching element is returned. If not found, returns false. array_search(value, array, strict), when the amount of data is relatively large, it is more appropriate to use array_key_exists, but it takes up a lot of memory,

The array structures are: array(1, 2, 3, ..) and array(1 => true, 2 => false, ..), and the memory usage ratio is 1:2.
The details are related to the internal implementation. The first and second data structures in PHP are similar, both are associative arrays.

Other supplements:

To find whether an element is in an array, there are three methods:

in_array 'Function searches for a given value in an array. in_array(value,array,type)type optional. If this parameter is set to true, it is checked whether the type of the searched data and the value of the array are the same.
array_key_exists 'array_key_exists() function determines whether the specified key exists in an array. If the key exists, it returns true, otherwise it returns false.

array_key_exists(key,array)

array_search 'array_search() function is the same as in_array(), searching for a key value in an array. If the value is found, the key of the matching element is returned. If not found, returns false.

array_search(value,array,strict)

From this point of view, when the amount of data is not large, such as less than 1000, any search method can be used, and it will not become a bottleneck;
When the amount of data is relatively large, it is more appropriate to use array_key_exists.
Of course the memory occupied by array_key_exists here is relatively large. According to calculations
the array structure is: array(1, 2, 3, ..) and array(1 => true, 2 => false, ..)
Their memory usage ratio is 1:2;
This is related to the internal implementation. In fact, the first and second data structures in PHP are similar, both are associative arrays.

http://www.bkjia.com/PHPjc/813134.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/813134.htmlTechArticleMethod 1: Use in_array(value,array,type) type is optional. If this parameter is set to true, it is checked whether the type of the searched data and the value of the array are the same. Copy the code The code is as follows...