How to output the contents of an array with PHP return value

In PHP, there are many cases where the return value is an array. We need to know how to output these arrays to the page or log file in order to better debug and view the running results of the program. This article will introduce several common methods to help you master how to output the content of PHP return value as an array.

1. Use the var_dump function to output content

The var_dump() function is a function in PHP used to output variable data types and values. It is also applicable to array types. We can use the var_dump() function to output the variable whose return value is an array to the terminal or web page, so that we can view the structure and element values ​​of the array.

The following is a simple sample code:

<?php
function getUserInfo($id) {
    $userInfo = array(
        &#39;name&#39; => '张三',
        'age' => 30,
        'gender' => '男'
    );
    return $userInfo;
}
$userInfo = getUserInfo(1001);
var_dump($userInfo);
?>

In the above code, we define a getUserInfo() function that returns an array containing user information. Outside the function, we call this function, assign the returned array to the $userInfo variable, and pass it to the var_dump() function to dump the array contents.

Execute this code, we can see the following content on the page:

array(3) { ["name"]=> string(6) "张三" ["age"]=> int(30) ["gender"]=> string(3) "男" }

The output result contains 3 elements of the array, and the key and value of each element are displayed. Elements of string type also display their length. Although this method can fully display the internal structure of the array, the amount of information is a bit complicated and may not be concise and clear enough.

2. Use the print_r function to output content

Another common way to output an array is to use the print_r() function. Different from the var_dump() function, the print_r() function does not display the type and length of the element, but only displays the value corresponding to the key value, which is more concise and easy to understand.

The following is a sample code that uses the print_r() function to output an array:

<?php
function getUserInfo($id) {
    $userInfo = array(
        &#39;name&#39; => '张三',
        'age' => 30,
        'gender' => '男'
    );
    return $userInfo;
}
$userInfo = getUserInfo(1001);
print_r($userInfo);
?>

Executing this code, we can see the following on the page:

Array ( [name] => 张三 [age] => 30 [gender] => 男 )

Output The result only contains the keys and values ​​of the array, without displaying type and length information. This approach can effectively focus on the contents of the array, making it easier to read and understand.

3. Use JSON encoding to output the array

In addition to the above two methods, we can also serialize the array into JSON format, and then output it to the page through functions such as echo or print. JSON is a lightweight data exchange format widely used in various programming languages ​​for data transmission and storage. PHP provides the json_encode() function to convert the array into JSON format, and we can use this function to output the array content.

The following is a sample code that uses the json_encode() function to output an array:

<?php
function getUserInfo($id) {
    $userInfo = array(
        &#39;name&#39; => '张三',
        'age' => 30,
        'gender' => '男'
    );
    return $userInfo;
}
$userInfo = getUserInfo(1001);
echo json_encode($userInfo);
?>

Executing this code, we can see the following on the page:

{"name":"张三","age":30,"gender":"男"}

Output The result is a JSON string containing the array's key and value information. When using this method, we need to pay attention to the following points:

1. To output JSON format, the array must be converted into JSON form first, which requires the use of the json_encode() function;
2. To output an array that has been converted into JSON format, you can use output functions such as echo or print;
3. The output result is a string type, and JSON decoding needs to be performed on the receiver to get the original array structure.

4. Use foreach loop to output content

The above three methods output the array as a whole to the page or log file, and cannot process each element of the array one by one. If we need to process the array elements one by one, we can use a foreach loop to achieve this.

The following is a sample code that uses a foreach loop to output array elements:

<?php
function getUserInfo($id) {
    $userInfo = array(
        &#39;name&#39; => '张三',
        'age' => 30,
        'gender' => '男'
    );
    return $userInfo;
}
$userInfo = getUserInfo(1001);
foreach ($userInfo as $key => $value) {
    echo $key . ": " . $value . "\n";
}
?>

Execute this code, we can see the following on the page:

name: 张三
age: 30
gender: 男

Output results Displays one element per line, with keys and values ​​separated by colons and spaces. This method can process array elements one by one, and with slight changes can achieve more output formats, such as HTML tables, etc.

The above are four common methods in PHP that output return values ​​as arrays. They each have their own advantages and disadvantages and are suitable for different scenarios and needs. In actual development, we need to choose different output methods according to needs, and continue to learn more methods to improve the readability and maintainability of the code.

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