How to get URL address parameters in PHP

PHP, as a classic server-side scripting language, is often used together with the HTTP protocol. Through HTTP requests, PHP can obtain various data from the client, such as form submission, cookie information, HTTP request headers, etc. Among them, obtaining URL address parameter data is also a very common operation in PHP. However, due to the different encoding and delivery methods of URL address parameters, we may encounter some errors when obtaining these parameters. This article will introduce how PHP obtains URL address parameters and solves errors that may be encountered when obtaining URL address parameters.

1. Obtain URL address parameters

In PHP, we can use two super global variables $_GET and $_REQUEST to obtain URL address parameters. These two variables are widely used in PHP. The difference between them is that the $_GET variable can only obtain URL address parameters, while the $_REQUEST variable can obtain all acquisition information, including form submission, cookie information, HTTP request headers, etc. Therefore, in order to improve server performance, we should first use the $_GET variable to obtain URL address parameters. The following is a sample code that uses the $_GET variable to obtain URL address parameters:

//获取URL地址中name参数的值
$name = $_GET['name'];

//获取URL地址中id参数的值
$id = $_GET['id'];

2. Common mistakes

1. Character encoding issues

In the URL address The passed parameters may be in Chinese. If correct encoding and decoding are not performed, garbled characters will appear or the parameter values ​​cannot be obtained. At this time, we can use PHP's urlencode() and urldecode() functions to solve the problem. The urlencode() function converts Chinese characters into URL encoding, and the urldecode() function decodes URL-encoded characters into Chinese characters. The following is a code example:

//编码中文字符
$name = urlencode('张三');
$url = "http://example.com?id=1&name=".$name;

//解码中文字符
$name = urldecode($_GET['name']);

2. The parameter does not exist

When obtaining the URL address parameter, if the parameter does not exist, it may cause an undefined variable error in the code . To solve this problem, we can use the isset() function to determine whether the variable exists. The following is a code example:

//判断name参数是否存在
if(isset($_GET['name'])) {
    $name = $_GET['name'];
} else {
    $name = '未定义';
}

3. Parameter type problem

When the URL address parameter is passed, a type mismatch may occur. For example, if a parameter value that is originally an integer type is incorrectly passed into a string type, we need to use the PHP cast function to convert the parameter into the correct type. The following is a code example:

//获取age参数，强制转换为整型类型
$age = (int)$_GET['age'];

//获取is_login参数，强制转换为布尔类型
$is_login = (bool)$_GET['is_login'];

3. Summary

Through the introduction of this article, we can learn how PHP obtains URL address parameters and how to handle errors that may occur when obtaining parameters. In actual development, we need to pay attention to the following points:

1. Correctly encode and decode URL address parameters to prevent garbled characters or inability to obtain parameter values.
2. Use the isset() function to determine whether the variable exists to prevent errors of undefined variables.
3. Use PHP cast function to convert parameters into the correct type to prevent type mismatch problems.

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