Summary of tips for using non-repeating elements in php arrays

In PHP programming, array is a very common data type, which can store multiple data values ​​​​in one variable and can easily operate on these data. In PHP, sometimes we need to deduplicate elements in an array. In this case, we can use the trick of removing duplicate elements in PHP arrays.

1. Use the array_unique() function

The most common way to deduplicate an array is to use the PHP built-in function array_unique(). This function can remove duplicate values ​​in the array and return a new one. array. This function has an optional parameter $sort_flags, which can control how the output results are sorted.

For example, the following code demonstrates how to use the array_unique() function to remove duplicate values ​​in the array $numbers:

$numbers = array(1,2,2,3,4,4,5,5);

// 去除数组中的重复值
$new_numbers = array_unique($numbers);

// 输出去重后的数组
print_r($new_numbers);

Run the above code, the output result is:

Array
(
    [0] => 1
    [1] => 2
    [3] => 3
    [4] => 4
    [6] => 5
)

2. Use foreach loop

In addition to using the array_unique() function, we can also use the foreach() loop to achieve array deduplication. The specific method is to traverse each element of the array. If the element does not appear before, add it to the new array, otherwise skip the element.

For example, the following code demonstrates how to use a foreach loop to implement array deduplication:

$numbers = array(1,2,2,3,4,4,5,5);

// 去除数组中的重复值
$new_numbers = array();
foreach($numbers as $value) {
    if(!in_array($value, $new_numbers)){
        $new_numbers[] = $value;
    }
}

// 输出去重后的数组
print_r($new_numbers);

Run the above code, the output result is the same as the first method.

3. Use the array_flip() function

In addition to the above methods, you can also use the array_flip() function to remove duplicate values ​​in the array. This function swaps the array keys, using the values ​​as keys, and returns a new array. Since key names are unique, duplicate values ​​are only retained once in the new array.

For example, the following code demonstrates how to use the array_flip() function to implement array deduplication:

$numbers = array(1,2,2,3,4,4,5,5);

// 去除数组中的重复值
$new_numbers = array_flip(array_flip($numbers));

// 输出去重后的数组
print_r($new_numbers);

Run the above code and the output will be the same.

Summary:

Through the above three methods, we can easily complete the PHP array deduplication operation. In actual programming, you can choose the method that best suits you according to the specific situation to make the program more concise and efficient.

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