How to define and use two-dimensional custom arrays in php

PHP, as a popular server-side scripting language, is widely used in web development and application development. During the development process, we often need to use arrays to save and store data, and PHP provides very flexible and convenient array processing functions.

Two-dimensional array is a very commonly used array type in PHP. It can be used to represent and store tables, matrices, and multidimensional data. This article will introduce how to define and use two-dimensional custom arrays.

1. What is a two-dimensional custom array?

In PHP, an array is a data structure used to store a set of values. A two-dimensional array refers to an array whose element itself is an array, also called a multi-dimensional array. A custom array refers to a self-defined array, that is, an array that is not created through the array functions provided by the language.

Two-dimensional custom array refers to a custom two-dimensional array, which consists of a set of rows and a set of columns, and can handle relatively complex data well.

2. How to define a two-dimensional custom array?

In PHP, we can use the array() function to define an empty array. If we want to define a two-dimensional array, we can continue to use array variables in the first array element, as shown in the following example:

$array = array(
    array('apple', 12, 2),
    array('banana', 7, 3),
    array('orange', 9, 4)
);

In the above code, we define a three-row and three-column Array, the first column is the name of the fruit, the second column is the price, and the third column is the quantity.

In addition to using the array() function, we can also use square brackets to define multi-dimensional arrays, as shown in the following example:

$array[0][0] = 'apple';
$array[0][1] = 12;
$array[0][2] = 2;

$array[1][0] = 'banana';
$array[1][1] = 7;
$array[1][2] = 3;

$array[2][0] = 'orange';
$array[2][1] = 9;
$array[2][2] = 4;

The above code is equivalent to the previous code, both are definitions A two-dimensional array with three rows and three columns.

3. How to access a two-dimensional custom array?

There are two ways to access the elements of a two-dimensional array: using subscripts or using loop statements.

We can think of the subscripts of the two-dimensional array as coordinates. The first subscript represents the row, and the second subscript represents the column. As shown in the following code, we can get the value of the two-dimensional array element through the subscript:

echo $array[0][0];    // 输出：apple
echo $array[0][1];    // 输出：12
echo $array[0][2];    // 输出：2

If you need to access the entire two-dimensional array, you can use a nested loop statement, as shown in the following example :

for ($i = 0; $i < count($array); $i++) {
    for ($j = 0; $j < count($array[$i]); $j++) {
        echo $array[$i][$j] . &#39; &#39;;
    }
    echo "<br>";
}

The above code will output the contents of the entire two-dimensional array.

4. How to add elements to a two-dimensional custom array?

What needs to be noted when adding elements to a two-dimensional array is that we need to know the location of the added element, that is, the subscript of the row and column.

Suppose we need to add a new element to the above array: "pear", the price is 10, and the quantity is 5. We can write it like this:

$array[] = array('pear', 10, 5);

// 或者

$array[count($array)] = array('pear', 10, 5);

Two ways to write the above code The effect is the same, adding a new element to the end of the array.

5. How to delete elements from a two-dimensional custom array?

To delete elements from a two-dimensional array, you need to use the unset() function in PHP, which can delete the specified element. For example, if we want to delete elements in $arry1, we can write like this:

unset($array[1][2]);

6. Summary

This article introduces how to define, access, add and delete 2D customizations array. Two-dimensional arrays are widely used in PHP, especially in processing tables, matrices, images and multi-dimensional data, and play a very important role.

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