How to loop through multidimensional array in PHP

How to loop through a multidimensional array in PHP

In PHP, an array is a powerful data structure that can hold multiple values. Multidimensional arrays are a further extension of arrays and can accommodate multiple arrays. Loop traversal is a common operation method when dealing with multi-dimensional arrays. This article will introduce how to use different loop methods to traverse multi-dimensional arrays in PHP and provide corresponding code examples.

1. Use for loop to traverse multi-dimensional arrays

The for loop is one of the most common and widely used loop methods. You can traverse multi-dimensional arrays by nesting multiple for loops. . The following is a sample code:

$array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];

for ($i = 0; $i < count($array); $i++) {
    for ($j = 0; $j < count($array[$i]); $j++) {
        echo $array[$i][$j] . " ";
    }
    echo "
";
}

In the above code, $array is a multidimensional array containing 3 arrays. Use two nested for loops to traverse the outer array and inner array respectively, and use the echo statement to output each element in the array.

2. Use foreach loop to traverse multi-dimensional arrays

The foreach loop is a more concise and convenient way to traverse an array, and can automatically traverse each element in the array. When dealing with multi-dimensional arrays, you can traverse the multi-dimensional array by nesting multiple foreach loops. The following is a sample code:

$array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];

foreach ($array as $subArray) {
    foreach ($subArray as $value) {
        echo $value . " ";
    }
    echo "
";
}

In the above code, $array is the same as in the previous example, using two nested foreach loops to traverse the multidimensional array. In each traversal, the current element is assigned to the variable $value and output using the echo statement.

3. Use recursive functions to traverse multi-dimensional arrays

The recursive function is a more flexible and scalable way to traverse multi-dimensional arrays. It can call itself recursively to process the array. every element. The following is a sample code:

$array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];

function traverseArray($array)
{
    foreach ($array as $element) {
        if (is_array($element)) {
            traverseArray($element);
        } else {
            echo $element . " ";
        }
    }
}

traverseArray($array);

In the above code, a recursive function named traverseArray is defined. The function uses a foreach loop internally to traverse the array. When it encounters a subarray, it calls itself to process the subarray; when it encounters an element, it outputs it directly. With recursive calls, you can iterate over all elements of a multidimensional array.

Summary:

In PHP, looping through multi-dimensional arrays is a common and important operation. This article introduces the use of for loops, foreach loops and recursive functions to traverse multi-dimensional arrays, and provides corresponding code examples. Based on actual needs and personal preferences, you can choose a suitable way to process multi-dimensional arrays. Mastering this knowledge will help improve the efficiency and simplicity of your code.

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