How to use two-dimensional array in php

Two-dimensional array is to store multiple arrays in one array. In PHP, you can use arrays to store multiple key-value pairs, which can be integers, strings, Boolean, etc.

Let’s take a look at how to define a two-dimensional array in PHP and how to access its values.

Define a two-dimensional array

In PHP, defining a two-dimensional array is very simple, you just need to include another array in the array. Such as the following example:

// 定义一个二维数组
$myArray = array(
    array(1, 2, 3),
    array(4, 5, 6),
    array(7, 8, 9)
);

The above code defines a two-dimensional array containing 3 arrays, each array contains 3 elements. As you can see, each array is enclosed by a bracket, and then these arrays are enclosed by a curly bracket.

Accessing two-dimensional arrays

Accessing values ​​in two-dimensional arrays is also very simple and can be accessed using subscripts. For example:

// 访问二维数组中的值
echo $myArray[0][0]; // 输出 1
echo $myArray[1][1]; // 输出 5
echo $myArray[2][2]; // 输出 9

In the above code, $myArray[0][0] means accessing the first element of the first array, which is 1. In the same way, $myArray[1][1] accesses the second element of the second array, which is 5.

Traversing a two-dimensional array

Traversing a two-dimensional array is also very simple. You can use the foreach statement provided by PHP. Such as the following example:

// 遍历二维数组
foreach ($myArray as $item) {
    foreach ($item as $value) {
        echo $value . ' ';
    }
    echo '<br>';
}

The above code outputs all the values ​​in the entire two-dimensional array. The values ​​​​of each array are separated by spaces. After the value of each array is output, the line breaks.

Commonly used two-dimensional array functions

In addition to the basic operations introduced above, PHP also provides many commonly used two-dimensional array functions. Some of them are described below.

1. count Function

count The function is used to count the number of one-dimensional arrays in a two-dimensional array. Its syntax It is:

$count = count($myArray);

This function returns the number of one-dimensional arrays contained in $myArray, which is 3.

2. array_push Function

array_push The function is used to add a one-dimensional array to the end of a two-dimensional array. The syntax is:

$lastArray = array(10, 11, 12);
array_push($myArray, $lastArray);

This function adds a new array containing 3 elements to the end of the two-dimensional array.

3. array_column Function

array_column The function is used to return the value of the specified column in the two-dimensional array. Its syntax is :

$newArray = array_column($myArray, 1);

This function returns a new array containing the elements in the second column of $myArray.

Summary

Two-dimensional array is a very commonly used data type in PHP, which can store more complex data structures. When using two-dimensional arrays, we need to pay attention to how subscripts of different dimensions are accessed. Mastering the use of two-dimensional arrays and commonly used functions can allow us to process and operate data more easily.

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