Remove duplicate values from php array

PHP array is a very convenient and powerful data structure. It provides many operating tools to enable developers to process data more efficiently. When we are dealing with arrays, we often encounter situations where we need to remove duplicate elements from the array. This article will introduce how to remove duplicate elements from an array in PHP.

1. array_unique() function

array_unique() function is a common deduplication method in PHP. It will remove duplicate elements and only retain the unique element in the array.

array_unique() function usage:

$array = array('apple', 'banana', 'orange', 'banana', 'peach');
$result = array_unique($array);
print_r($result); // Output: Array ( [0] => apple [1] => banana [2] => orange [4] => peach )

2. Use loop traversal

In addition to using the array_unique() function, we can also use loop traversal to remove duplicate elements in the array. Traverse the array and record the elements that have already appeared, and skip directly when duplicate elements are encountered.

$unique_array = array();
$input_array = array('apple', 'banana', 'orange', 'banana', 'peach');
foreach ($input_array as $element) {

if (!in_array($element, $unique_array)) { array_push($unique_array, $element); }

}
print_r($unique_array); // Output: Array ( [0] => apple [1] => banana [2] => orange [4 ] => peach )

In this example, we use a foreach loop to traverse the original array $input_array. In each loop, we use the in_array() function to determine whether the current element has appeared. If it doesn't appear before, we add the element to the $unique_array array. Note that we use the array_push() function when adding elements, because this function can add one or more elements to the end of the array.

3. Use the array_diff() function

array_diff() function can return the difference between two arrays, that is, return elements that only appear in one array. Therefore, we can use the array_diff() function to remove duplicate elements from an array.

$unique_array = array_diff($input_array, array(''));
print_r($unique_array); // Output: Array ( [0] => apple [1] => banana [2] => orange [4] => peach )

In this example, we use $input_array and an array containing empty string elements to do the difference operation. Since it is impossible to have two empty string elements in an array, the array_diff() function removes all empty string elements.

Summary

The above are several methods to remove duplicate elements from PHP arrays. In actual development, we can choose different methods according to different application scenarios. For scenarios with higher performance requirements, you can use the in_array() function; if the array elements are not strings, you can use the array_keys() function; if you need to keep the key-value relationship unchanged, you can use the array_intersect_assoc() function.

No matter which method we choose, we should choose the method that best suits us based on the actual situation. At the same time, remember to add necessary comments to the code for easier maintenance and reading.

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