As a widely used server-side scripting language, PHP provides numerous math, string, array, file and other function libraries to facilitate developers to implement various functions. Among them, the array_unique() function plays an important role in array deduplication. This article will introduce the usage and precautions of this function in detail.
array_unique() function is used to remove duplicate elements from an array and return a new array that does not contain duplicate elements.
Function syntax
array_unique(array $array, int $sort_flags = SORT_STRING): array
$array: required, the array to be processed
$sort_flags: optional, defines the sort Way. Possible options are:
The return value is the processed array.
The following will demonstrate how to use the array_unique() function to remove duplicate arrays.
<?php $array = array(1, 2, 3, 2, 4); $result = array_unique($array); print_r($result); ?>
Running results:
Array ( [0] => 1 [1] => 2 [2] => 3 [4] => 4 )
When the same key-value pair exists in the processed array, the array_unique() function only retains The first key-value pair, discard other duplicate key-value pairs. For example, processing the following array:
$array = array("foo", "bar", "foo", "baz", "bar");
array_unique() will only retain the first "foo" and the first "bar", and remove other duplicate elements. The result is:
Array ( [0] => foo [1] => bar [3] => baz )
In addition, since the array_unique() function is a relatively time-consuming operation, the efficiency will be affected to a certain extent when processing large-scale arrays. Therefore, in actual development, attention needs to be paid to the balance between the number of array elements and processing efficiency.
array_unique() function is a deduplication function in the PHP array function library, which can quickly remove duplicate elements in the array. When using it, you need to pay attention to the types and formats of its parameters and return values, and carefully consider the efficiency of processing large-scale arrays to ensure the stability and efficiency of the program.
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