Detailed explanation of the methods and precautions for converting php urlencode to Chinese

In the process of web development, it is often necessary to convert user-entered data into usable URL parameters to facilitate passing it to the back-end program for processing. In this process, urlencode is a very commonly used function, which can convert various characters into an encoding form that can be used in URLs. However, the way Chinese characters are encoded can often be confusing when using urlencode. In this article, we will introduce in detail the method of converting php urlencode to Chinese and related precautions.

1. The purpose and basic usage of the urlencode function

The urlencode function is a built-in function in PHP. Its main function is to convert a string into a URL safely. String. When you need to pass some data containing special characters into URL parameters, you need to use urlencode for encoding to ensure the correctness of the URL.

The basic usage of urlencode is very simple. You only need to pass in the string to be encoded. The following is a simple sample code:

$url = "http://example.com?name=" . urlencode("张三") . "&age=20";
echo $url;

The above code will output a result similar to the following:

http://example.com?name=%E5%BC%A0%E4%B8%89&age=20

As you can see, urlencode converts the Chinese character "Zhang San" into "Zhang San" form and passed to the backend handler through URL parameters.

2. Urlencode Chinese character encoding method

As shown in the sample code above, urlencode converts Chinese characters into a series of special character combinations. This is because only a part of the characters in the ASCII character set can be used in the URL, and non-ASCII characters such as Chinese cannot be used. For non-ASCII characters, variable length encoding needs to be used to encode them into a character set that can be used in the URL.

In the php urlencode function, the encoding method of Chinese characters mainly uses the URL encoding method under UTF-8 encoding. UTF-8 is a variable-length encoding method that can represent all Unicode characters into 1~4 bytes. URL encoding represents Chinese characters in the form of "%xx", where xx represents the hexadecimal ASCII code value of the character.

For example, the UTF-8 encoding of the Chinese character "Zhang San" is "E5 BC A0 E4 B8 89", where each character is represented as a hexadecimal number, that is, "Zhang San". This way, urlencode can correctly convert it into an encoded form usable in the URL.

3. Precautions when using urlencode

Although urlencode can easily convert Chinese characters into URL encoding form, you also need to pay attention when using it in practice. Some details. The following are some things to note when using urlencode:

1. urlencode only encodes specific characters, and for most characters in the ACII character set, encoding is not required. For example, English, numbers, and some symbols such as "-", "_", ".", etc. do not need to be converted to urlencode and can be passed directly.
2. urlencode can only be used to encode characters and cannot be used to re-encode already encoded strings. If you need to decode a string that has been urlencoded, you should use the urldecode function to perform the decoding operation.
3. PHP's urlencode function is implemented according to the RFC 3986 standard, which is somewhat different from the earlier RFC 1738 standard. Therefore, when using urlencode, you need to pay attention to the connection method with the back-end processor to avoid data transmission errors.

4. Summary

In php, urlencode is a very useful function, which can help us encode various characters into the encoding used by the URL form to ensure the correctness of the URL. When you need to use urlencode, you should pay attention to the encoding and usage of Chinese characters, as well as the connection method with the back-end program, so that you can give full play to the role of urlencode.

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