Learn the PHP array_unique function and master how to remove duplicate values

In daily programming, sometimes we need to deduplicate an array. At this time, we can use the array_unique function in PHP. This article will introduce the usage of array_unique function and lead readers to master how to use it to remove duplicate values.

1. Usage of array_unique function

The array_unique function is used to remove duplicate values ​​in an array and return a new array.

Its syntax format is:

array_unique(array $array, int $sort_flags = SORT_STRING): array

Among them, $array represents the array to remove duplicate values, $sort_flags represents optional parameters, used to specify the sorting method, SORT_STRING represents sorting by string , if not specified, the default is to sort by the value itself.

2. Example Demonstration

Let’s look at a simple example demonstration. Suppose there is an array $fruits:

$fruits = array("apple", "banana", "orange", "banana", "grape", "apple");

There are two in this array "apple" and "banana", we need to remove them and leave only other fruits. We can use the array_unique function to achieve the goal:

$unique_fruits = array_unique($fruits);

At this time, the value of $unique_fruits is:

array("apple", "banana", "orange", "grape");

3. Notes

You need to pay attention to the following points when using the array_unique function:

(1) The function only deduplicates one-dimensional arrays, and multi-dimensional arrays need to be processed recursively. ;

(2) The key values ​​of the array will not be retained, and the subscripts of all elements will be re-indexed after deduplication;

(3) If there are both strings and numbers in the array For repeated values ​​of type, the function will convert the numeric type into a string type and then remove the duplicates;

(4) For NULL and empty string "" in the array, they are regarded as the same value and will only be retained One, and which one is kept depends on the position in the array.

4. Summary

The array_unique function is a very convenient and practical function built into PHP. Use it to easily remove duplicate values ​​from an array and reduce redundant operations when processing various data. However, you need to pay attention to some details when using it, so that you can give full play to the role of this function. I hope this article can help readers quickly master the method of using the array_unique function to remove duplicates.

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