php remove duplicate values ​​from array

With the rapid development of Internet technology, various programming languages ​​are also constantly updated and developed. Among them, PHP, as a powerful language for developing Web applications, has received widespread attention and use. In PHP programming, arrays are one of the most commonly used data types, and the problem of dealing with duplicate values ​​in arrays is also one of the problems that PHP developers often encounter. This article will introduce how to delete duplicate values ​​in an array in PHP.

Method 1: array_unique

PHP provides a built-in function array_unique(), which can be used to delete duplicate values ​​in the array. array_unique()The function will return a new array that contains all the unique values ​​in the input array.

Using the array_unique() function is very simple, you only need to pass in the array variable to be processed. For example:

$arr = array(1, 2, 2, 3, 3, 4);
$newArr = array_unique($arr);
print_r($newArr);

The output of the above code is as follows:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [5] => 4
)

As you can see, the duplicate values ​​2 and 3 have been deleted.

Method 2: Loop traversal

If you want to handwrite a method to delete duplicate values ​​​​in an array, it is also very simple. Here we can use loop traversal to achieve. The specific steps are as follows:

1. Define a new array to store unique values
2. Traverse each value in the original array. If the value does not exist in the new array, Then store the value in the new array
3. Return the new array

The code to implement this method is as follows:

function removeDuplicates($arr) {
    $newArr = array();
    foreach($arr as $val) {
        if(!in_array($val, $newArr)) {
            $newArr[] = $val;
        }
    }
    return $newArr;
}

The code to call this method is as follows:

$arr = array(1, 2, 2, 3, 3, 4);
$newArr = removeDuplicates($arr);
print_r($newArr);

This method can also achieve the purpose of deleting duplicate values ​​in the array, and the output result is the same as using the array_unique() function.

Summary

The above introduces two methods for PHP to delete duplicate values ​​​​in an array: using the array_unique() function and loop traversal. Both methods can achieve the purpose of removing duplicate values ​​​​in an array. Which method to use depends on the developer's personal preference and actual needs. No matter which method is used, attention should be paid to its execution efficiency. Choosing a more efficient method can improve the running efficiency of the program.

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