Illegal Multibyte Sequences: What They Are & How to Handle Them

An illegal multibyte sequence refers to a sequence of bytes that does not conform to the rules of a specific character encoding scheme, such as UTF-8 or UTF-16. In these encoding schemes, characters are represented by multiple bytes, and each byte in the sequence must follow certain rules to be considered valid.

For example, in UTF-8, a multibyte sequence must start with a specific byte pattern to indicate the number of bytes that follow. If a byte sequence does not start with a valid pattern or contains invalid byte values, it is considered an illegal multibyte sequence.

Illegal multibyte sequences can occur due to various reasons, such as:

1. Incorrectly encoded data: If a text file or input data is encoded using a different character encoding scheme than what is expected, it can result in illegal multibyte sequences.

2. Data corruption: If a file or data is corrupted during transmission or storage, it can lead to invalid byte sequences.

Handling illegal multibyte sequences is important to ensure the integrity and correctness of data. When encountering such sequences, it is common to use error handling mechanisms, such as replacing the illegal sequences with a placeholder character or reporting an error to the user.