How to store two-dimensional array in php

In PHP, two-dimensional arrays are a very common data type, usually used to store tabular or matrix data. A two-dimensional array is an array composed of multiple one-dimensional arrays. It is usually represented in a program as a nested array, where each sub-array represents a one-dimensional array. In this article, we will discuss how to store two-dimensional arrays in PHP and demonstrate how to manipulate these arrays through examples.

1. Create a two-dimensional array

Creating a two-dimensional array in PHP is very simple. You only need to create a nested array when defining the array. The code is as follows:

$matrix = array(
    array(1, 2, 3),
    array(4, 5, 6),
    array(7, 8, 9)
);

The above code creates a two-dimensional array containing three one-dimensional arrays, each one-dimensional array containing three integers. We can also use a for loop to create a two-dimensional array with multiple rows and columns. The example is as follows:

$rows = 4;
$cols = 5;
$matrix = array();
for ($i = 0; $i < $rows; $i++) {
    $row = array();
    for ($j = 0; $j < $cols; $j++) {
        $row[] = $i * $cols + $j;
    }
    $matrix[] = $row;
}

In the above code, we use the for loop to create a two-dimensional array containing 4 rows and 5 columns. And store the row and column index values ​​in the array.

2. Accessing two-dimensional arrays

Accessing two-dimensional arrays in PHP is very simple. You only need to use square brackets to specify the index values ​​of the rows and columns you want to access. For example, to access the second row and third column elements of the $matrix array created above, you can use the following code:

echo $matrix[1][2];

The above code will output the second row and third column element 6 of the $matrix array.

We can also use the for loop to traverse the entire two-dimensional array, the example is as follows:

$rows = count($matrix);
$cols = count($matrix[0]);
for ($i = 0; $i < $rows; $i++) {
    for ($j = 0; $j < $cols; $j++) {
        echo $matrix[$i][$j] . &#39; &#39;;
    }
    echo &#39;<br>';
}

In the above code, we use the for loop to traverse the entire two-dimensional array $matrix, and use the echo statement Output the array elements to the page in sequence.

3. Operating two-dimensional arrays

It is also very convenient to operate two-dimensional arrays in PHP. We can use various array functions to operate two-dimensional arrays. The following are some commonly used operation functions:

1. array_push(): Add one element or multiple elements to the end of a two-dimensional array.

$row = array(10, 11, 12);
array_push($matrix, $row);

The above code adds a new one-dimensional array to the end of the $matrix array.

2. array_pop(): Remove and return the last element of the array.

$row = array_pop($matrix);

The above code deletes and returns the last one-dimensional array of the $matrix array.

3. array_shift(): Remove and return the first element of the array.

$row = array_shift($matrix);

The above code removes and returns the first one-dimensional array of the $matrix array.

4. array_unshift(): Adds one or more elements to the beginning of the array.

$row = array(-1, 0, 1);
array_unshift($matrix, $row);

The above code adds a new one-dimensional array to the beginning of the $matrix array.

5. array_slice(): Remove a segment of elements from the array.

$row = array_slice($matrix, 1, 2);

The above code takes two consecutive elements starting from the second element from the $matrix array and puts them into a new array $row.

4. Summary

Storing two-dimensional arrays in PHP is very simple. You only need to create a nested array when defining the array. It is also very convenient to access and operate two-dimensional arrays. You can use various array functions to operate on two-dimensional arrays. In actual development, two-dimensional array is a very commonly used data structure, and it is very important to master its usage.

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