PHP's urldecode() function: How to decode a URL-encoded string into a raw string and handle decoding errors

PHP’s urldecode() function was created in PHP4 and is a common URL decoding method. URL encoding is a method of converting non-English characters in a URL into special characters in order to transmit the URL to the server or otherwise process the URL. The urldecode() function restores these special characters to the original string.

The syntax of this function is:

string urldecode ( string $str )

The parameter str represents the string that needs to be decoded, and the function will return the decoded original string.

However, when using the urldecode() function, it is easy to cause decoding errors, and special characters are not restored correctly. In PHP, it is recommended to use the rawurldecode() function instead of the urldecode() function to obtain a more reliable decoding effect.

Next, we will give specific code examples showing how to use PHP's rawurldecode() function to decode a URL-encoded string into a raw string and handle decoding errors.

<?php
// 示例1：使用urldecode()函数进行URL解码
$string = "Hello%20World!";
echo urldecode($string); // 输出：Hello World!

// 示例2：使用rawurldecode()函数进行URL解码
$string = "你好%20世界！";
echo rawurldecode($string); // 输出：你好 世界！

// 示例3：解决解码错误
$string = "Portland%3ESeattle";
$decoded = rawurldecode($string);
if($decoded == $string) {
  // 没有任何字符被解码，需要手动解码
  $decoded = str_replace("%3E", ">", $string);
}
echo $decoded; // 输出：Portland>Seattle
?>

In the above examples, Example 1 and Example 2 show the basic usage of URL decoding using the urldecode() and rawurldecode() functions respectively.

And Example 3 shows how to handle decoding errors. In this example, the original string is "Portland>Seattle", but the ">" symbol is encoded in the URL as ">". If you directly use the rawurldecode() function to decode, the ">" symbol will not be decoded correctly, and the decoding result will be "Portland>Seattle". Therefore, we need to manually decode, that is, use the str_replace() function to replace ">" with ">".

In short, the urldecode() function is a common URL decoding method in PHP. However, due to the higher possibility of decoding errors, it is recommended to use the rawurldecode() function to obtain more reliable decoding results.

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