How to output a two-dimensional array in php

PHP is a very popular programming language and the most commonly used language in web development. In PHP, arrays are a very basic and commonly used data structure, and two-dimensional arrays are even more common. A 2D array is like a large array made up of subarrays, each of which is a 1D array. This article will introduce how to output a two-dimensional array in PHP.

1. Use loop statements to traverse output

Using loop statements to traverse a two-dimensional array is the most basic and simple method. Generally speaking, you can use for, foreach, while and other loop statements. For a two-dimensional array, you can use a nested loop to iterate through each subarray and then iterate over the elements in each subarray. The following is a basic example:

$students = array(
    array("Name" => "Tom", "Age" => 20, "Gender" => "Male"),
    array("Name" => "Jane", "Age" => 21, "Gender" => "Female"),
    array("Name" => "Jack", "Age" => 22, "Gender" => "Male")
);
for ($i=0; $i<count($students); $i++) {
    echo "Student ".($i+1)."<br>";
    foreach ($students[$i] as $key => $value) {
        echo $key.": ".$value."<br>";
    }
    echo "<br>";
}

The output result is as follows:

Student 1
Name: Tom
Age: 20
Gender: Male

Student 2
Name: Jane
Age: 21
Gender: Female

Student 3
Name: Jack
Age: 22
Gender: Male

In this example, first we define a two-dimensional array $students, where each sub-array represents the information of a student, Including name, age and gender. Then, we use a for loop to traverse each student, and then use a foreach loop to traverse the student's information and output it line by line.

2. Use the print_r or var_dump function to output

If you just want to quickly view the structure and content of a two-dimensional array, you can use the print_r or var_dump function to output. These two functions are built-in functions of PHP and can be used to print debugging information. They can respectively output a form similar to printing array information and more detailed debugging information. The following is a simple example:

$students = array(
    array("Name" => "Tom", "Age" => 20, "Gender" => "Male"),
    array("Name" => "Jane", "Age" => 21, "Gender" => "Female"),
    array("Name" => "Jack", "Age" => 22, "Gender" => "Male")
);
echo "<pre class="brush:php;toolbar:false">";
print_r($students);
echo "

"; echo "

";
var_dump($students);
echo "

";

The output result is as follows:

Array
(
    [0] => Array
        (
            [Name] => Tom
            [Age] => 20
            [Gender] => Male
        )

    [1] => Array
        (
            [Name] => Jane
            [Age] => 21
            [Gender] => Female
        )

    [2] => Array
        (
            [Name] => Jack
            [Age] => 22
            [Gender] => Male
        )

)
array(3) {
  [0]=>
  array(3) {
    ["Name"]=>
    string(3) "Tom"
    ["Age"]=>
    int(20)
    ["Gender"]=>
    string(4) "Male"
  }
  [1]=>
  array(3) {
    ["Name"]=>
    string(4) "Jane"
    ["Age"]=>
    int(21)
    ["Gender"]=>
    string(6) "Female"
  }
  [2]=>
  array(3) {
    ["Name"]=>
    string(4) "Jack"
    ["Age"]=>
    int(22)
    ["Gender"]=>
    string(4) "Male"
  }
}

In this example, we use the print_r and var_dump functions to output the contents of the $students array, where echo "

 ";Used to format output. The print_r function prints the contents of the array, while the var_dump function outputs more detailed array information, including key name, type, length, etc. </p>
<p>3. Use json_encode output</p>
<p>Another way to output a two-dimensional array is to convert it to JSON format and then use the json_encode function to output it. JSON is a lightweight data exchange format that is widely used in modern web applications. The following is an example: </p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">$students = array(
    array("Name" => "Tom", "Age" => 20, "Gender" => "Male"),
    array("Name" => "Jane", "Age" => 21, "Gender" => "Female"),
    array("Name" => "Jack", "Age" => 22, "Gender" => "Male")
);
echo json_encode($students);

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The output result is as follows:

[{"Name":"Tom","Age":20,"Gender":"Male"},{"Name":"Jane","Age":21,"Gender":"Female"},{"Name":"Jack","Age":22,"Gender":"Male"}]

In this example, we use the json_encode function to convert the two-dimensional array $students into JSON format and then output it. The json_encode function converts the elements of the array into a JSON string, using square brackets to represent the entire array.

Summary

The above are three common ways to output PHP two-dimensional arrays, which are to use loop statements to traverse the output, to use the print_r or var_dump function to output, and to use json_encode to output. For different needs, you can choose different output methods to present data. In actual development, we often need to output arrays to web pages and adjust styles and layouts with HTML and CSS. This is also one of the important applications of PHP two-dimensional array output.

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