How to traverse output multi-dimensional array in php

As an extremely popular programming language, PHP is widely used in many Web application fields. Its powerful array operation function is a major feature of its active developer community. Arrays are an integral part of PHP programming, and multidimensional arrays are one of their most commonly used and powerful forms. In this article, we will focus on how to traverse output multi-dimensional arrays.

one. What is a multidimensional array

First of all, we need to understand what a multidimensional array is. In PHP, an array refers to an ordered list of data, and a multidimensional array is an array containing multiple arrays. Typically, multidimensional arrays are mainly used for storage and processing applications that require multi-layer data structures. For example, if we need to store student information for multiple classes, and each class also contains student name, gender, age and other information, we can store it through a multi-dimensional array.

two. How to define a multi-dimensional array

Defining a multi-dimensional array is relatively simple, and usually requires the use of nested array definitions, such as the following sample code:

// 定义一个包含多个数组的多维数组
$students = array(
    array('name'=>'Tom', 'gender'=>'male', 'age'=>19),
    array('name'=>'Lily', 'gender'=>'female', 'age'=>18),
    array('name'=>'Lucy', 'gender'=>'female', 'age'=>20),
);

The above code implements a multi-dimensional array containing multiple arrays Arrays, each containing the student's name, gender, and age.

three. How to traverse a multi-dimensional array

Traversing a multi-dimensional array is usually implemented using the foreach loop structure. The foreach loop structure is not only applicable to one-dimensional arrays, but also to multi-dimensional arrays. Let’s look at a sample code that traverses the above $students array:

// 遍历多维数组
foreach($students as $student){
    echo $student['name'].' '.$student['gender'].' '.$student['age'].'<br>';
}

In the above code, we use the foreach loop structure to traverse each element in the $students array, that is, each student object. The $student variable here represents the array object currently being looped to. We obtain the name, gender, and age of the student from the array through the array object subscript, and use the echo command to output the information of each student.

Four. How to edit multi-dimensional arrays

For editing operations of multi-dimensional arrays, it is usually necessary to use various operation functions of the array and multi-dimensional array subscript operations. Some of these functions are introduced below:

1. array_push function

array_push function is used to add elements to the end of an array. If we need to add a new student to the $students array, we can use the following code:

// 添加新的学生信息
$new_student = array('name'=>'Jack', 'gender'=>'male', 'age'=>21);
array_push($students, $new_student);

In the above code, we use the array_push function to add $new_student student information to the end of the $students array.

2. array_merge function

array_merge function is used to merge multiple arrays. If we need to merge the $students array and the $new_student array, we can use the following code:

// 合并多个数组
$new_student = array('name'=>'Jack', 'gender'=>'male', 'age'=>21);
$students = array_merge($students, array($new_student));

In the above code, we use the array_merge function to merge the two arrays together and assign the result to the $students array.

3. unset function

If we need to delete an element in a multi-dimensional array, we can use the unset function. For example, the following code will delete the first element in the $students array. elements.

// 删除数组元素
unset($students[0]);

The above code will delete the first element in the $students array, which is Tom’s student information.

five. Summary

This article mainly introduces how to operate and edit multi-dimensional arrays, including how to define multi-dimensional arrays, how to traverse multi-dimensional arrays, and how to use various array operation functions to edit multi-dimensional arrays. Multidimensional arrays are a very important data type in PHP programming. Proficient in the operation skills of multidimensional arrays will help us develop Web applications more effectively. At the same time, when we need to process multi-layer data structures, we can also use multi-dimensional arrays for data storage and processing more flexibly.

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