How to resolve errors encountered when using the PHP substr function?

If you encounter an error while using the PHP substr() function, you can generally resolve the issue by following these steps:

1. Check the parameters for accuracy: Make sure that the parameters passed to the substr() function are correct, including the string parameter and the length parameter. Ensure that the string parameter is a valid string and the length parameter is an integer.
2. Check the length of the string: Make sure that the length to be truncated does not exceed the actual length of the string. If the length to be truncated is greater than the string length, it will result in an error.
3. Check the string encoding: If the string contains non-ASCII characters (such as Chinese characters), make sure the encoding of the string is consistent with the default character encoding of PHP. You can use the mb_substr() function to extract strings containing non-ASCII characters.
4. Check if the string is empty: If the string to be trimmed is empty or null, it will result in an error. Make sure the string to be trimmed is not empty.
5. Check the PHP version: some PHP functions may not be available or behave differently in older versions. Make sure you are using the latest PHP version.

If none of the above steps resolve the issue, you can try checking error messages and searching for solutions. During development, you can also use var_dump() or print_r() to debug and view the value and type of variables to identify the problem.