How to achieve one-dimensional number combination without repetition in PHP

In PHP, the operation of merging one-dimensional arrays is quite common. Normally, we can merge arrays through array_merge or the " " operator. However, when merging arrays, sometimes we need to remove duplicate elements, so what should we do?

This article will introduce two deduplication methods based on array key values, through which non-duplicate one-dimensional arrays can be easily merged.

1. Use array_unique

array_unique function can deduplicate duplicate elements in the array and return an array without duplicate elements. This can be used to ensure that after merging There are no duplicate elements in the array.

First, we prepare two one-dimensional arrays $array1 and $array2:

$array1 = array('a', 'b', 'c');
$array2 = array('b', 'c', 'd');

Next, we use array_merge to merge the two arrays:

$result = array_merge($array1, $array2);

At this time, The result of $result is:

array('a', 'b', 'c', 'b', 'c', 'd')

As you can see, there are two repeated elements of 'b' and 'c' in $result. In order to remove these duplicate elements, we can use the array_unique function:

$result = array_unique($result);

At this time, the result of $result is:

array('a', 'b', 'c', 'd')

At this time, there are no duplicate elements in $result.

2. Use array key values ​​to deduplicate

In addition to using the array_unique function, we can also deduplicate by setting array key values.

The key value of the array must be unique, so we only need to use the elements in the array that need to be merged as the key value, so as to ensure that there are no duplicate elements in the merged array.

We can first define an empty array $result, then iterate through the two arrays to be merged and add the value of the element as a key value to $result, as shown below:

$array1 = array('a', 'b', 'c');
$array2 = array('b', 'c', 'd');

$result = array();
foreach($array1 as $value){
    $result[$value] = true;
}
foreach($array2 as $value){
    $result[$value] = true;
}

$result = array_keys($result);

This At this time, the result of $result is:

array('a', 'b', 'c', 'd')

At this time, there are no duplicate elements in $result.

It is worth noting that although the above method avoids using the array_unique function, it needs to set a temporary Boolean value as the value of the array. Therefore, when merging arrays, if the value of the array itself is a Boolean value type, There may be problems with this approach.

Summary

In PHP, merging one-dimensional arrays and removing duplicate elements is a very common operation. This article introduces two deduplication methods based on array key values, which are using the array_unique function and array key value deduplication. These methods can greatly simplify the process of array merging and quickly merge non-duplicate one-dimensional arrays. When using these methods, you need to choose the most suitable method according to the actual situation.

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