How to convert a two-dimensional array into a one-dimensional array in php

During development, you may encounter the need to convert a two-dimensional array into a one-dimensional array. This article will introduce how to perform this operation in PHP.

A two-dimensional array in PHP is an array composed of multiple one-dimensional arrays, while a one-dimensional array is an array composed of a single value. Therefore, to convert a two-dimensional array into a one-dimensional array, you need to extract all the values ​​​​in the one-dimensional array and then put them into the new one-dimensional array.

1. Use a loop to traverse a two-dimensional array

In PHP, you can use a loop to traverse a two-dimensional array and add the values ​​​​to a new one-dimensional array. The specific implementation is as follows:

$multiArr = array(array('apple', 'banana', 'pear'), array('cat', 'dog', 'lion'));

$singleArr = array();
foreach ($multiArr as $arr) {
    foreach ($arr as $value) {
        $singleArr[] = $value;
    }
}

print_r($singleArr);

In the above code, a two-dimensional array $multiArr is first defined, which contains two one-dimensional arrays. Then create an empty one-dimensional array $singleArr, and then use two nested foreach to loop through each one-dimensional array in $multiArr and among them value and adds the value to $singleArr. Finally, use the print_r() function to print out $singleArr, and the output result is:

Array
(
    [0] => apple
    [1] => banana
    [2] => pear
    [3] => cat
    [4] => dog
    [5] => lion
)

2. Use the call_user_func_array() function

In addition to looping, you can also use the call_user_func_array() function to convert a multi-dimensional array into a one-dimensional array. The specific code is as follows:

$multiArr = array(array('apple', 'banana', 'pear'), array('cat', 'dog', 'lion'));

$singleArr = call_user_func_array('array_merge', $multiArr);

print_r($singleArr);

In the above code, a two-dimensional array $multiArr is first defined, which contains two one-dimensional arrays. Then use the call_user_func_array() function. The first parameter is the array_merge function name, which means that the merge operation is to be performed. The second parameter is the $multiArr array, which means Multiple arrays to merge. The combined new array is the one-dimensional array $singleArr. Finally, use the print_r() function to print out $singleArr, and the output result is:

Array
(
    [0] => apple
    [1] => banana
    [2] => pear
    [3] => cat
    [4] => dog
    [5] => lion
)

3. Use the array_reduce() function

In addition to the above two methods, you can also use the array_reduce() function to convert a two-dimensional array into a one-dimensional array. The specific implementation is as follows:

$multiArr = array(array('apple', 'banana', 'pear'), array('cat', 'dog', 'lion'));

$singleArr = array_reduce($multiArr, 'array_merge', array());

print_r($singleArr);

In the above code, a two-dimensional array $multiArr is first defined, which contains two one-dimensional arrays. Then use the array_reduce() function. The first parameter is the $multiArr array, indicating the array to be merged. The second parameter is the array_merge function name. , indicating that a merge operation is to be performed, and the third parameter is an empty array, indicating that the initial one-dimensional array is an empty array. Finally, store the combined new array into the one-dimensional array $singleArr, and use the print_r() function to print the output result. The output result is the same as the first two methods:

Array
(
    [0] => apple
    [1] => banana
    [2] => pear
    [3] => cat
    [4] => dog
    [5] => lion
)

4. Summary

In this article, three methods of converting two-dimensional arrays into one-dimensional arrays are introduced. In actual development, you can choose the appropriate method according to your needs. For simple two-dimensional arrays, the first method of loop traversal may be easier to understand and implement; for more complex multi-dimensional arrays, the call_user_func_array() function and the array_reduce() function Might be more convenient.

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