Solution to PHP Fatal error: Call to undefined function mb_convert_encoding()

PHP is a popular server-side scripting language that is widely used in web development. However, when programming with PHP, users may encounter various errors and problems. This article will lead readers to learn how to solve a common error: PHP Fatal error: Call to undefined function mb_convert_encoding().

What is the mb_convert_encoding() function?

Before exploring how to solve this error, let's first understand the mb_convert_encoding() function. This is a built-in function of PHP that converts between different character sets and encodings.

Specifically, the mb_convert_encoding() function can convert a string from one character set and encoding to another. It can handle common character sets and encodings, such as UTF-8, GB2312, ISO-8859, and more.

The mb_convert_encoding() function is very useful, especially when you need to pass data between different systems and applications. However, sometimes you may encounter a problem: when using the mb_convert_encoding() function, PHP will throw a "Fatal error" error, prompting "Call to undefined function mb_convert_encoding()".

What is the reason for this error?

The reason for this error is that PHP does not configure the mbstring extension module correctly.

The mbstring extension module is a multi-byte string processing library provided by PHP. It provides many functions to process strings under different encodings and character sets. Before using mbstring functions in PHP, you need to install and enable the mbstring extension module.

If you forget to install or enable the mbstring extension module, or do not configure it correctly, PHP will throw a "Call to undefined function mb_convert_encoding()" error when you call the mb_convert_encoding() function, because PHP cannot find the definition of this function.

How to solve the error of mb_convert_encoding() function?

To resolve this error, you need to configure and enable the mbstring extension module. The following are some possible solutions:

1. Use parameters when compiling PHP

If you miss the mbstring extension module when compiling PHP, then you need to recompile PHP and add --with-mbstring parameter to support mbstring extension module. After compilation is complete, the mbstring extension module will be correctly installed and enabled.

2. Modify the php.ini file

If you have installed the mbstring extension module but still get an error when using the mb_convert_encoding() function, you need to edit the php.ini file and add or modify it. The following two lines:

extension=php_mbstring.dll //或者extension=mbstring.so，根据实际情况来确定
mbstring.encoding_translation=On

These two lines will open the mbstring extension module, thereby avoiding the "Call to undefined function mb_convert_encoding()" error.

3. Use a PHP framework or library

If you are using a framework or library developed based on PHP, you can try to use the multi-byte string processing provided by it directly in the code function, rather than the function of the mbstring extension module. These frameworks and libraries usually have their own character sets and encoding processing functions, such as the Str class in the Laravel framework, the Text class in the CodeIgniter framework, and so on.

Summary

In the PHP development process, the mb_convert_encoding() function is a very useful function. However, if PHP does not configure the mbstring extension module correctly, it will cause the "Call to undefined function mb_convert_encoding()" error. By recompiling PHP, modifying the php.ini file, or using functions provided by frameworks and libraries, you can resolve this error and continue programming and development smoothly.

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