what is a regex letter-only pattern?

A regular expression, or regex letter-only pattern is a type of advanced search technique used to search through text or strings for characters that only contain letters, either upper- or lower-case. This can prove useful in a variety of situations. For example, if you need to validate a user's input for a form, you may want to make sure the user does not include any non-letter characters such as numbers, symbols or whitespace.

Regex letter-only patterns are created by setting constraints to the characters that either must or must not be included in the pattern. For instance, when creating a regex letter search pattern, you can order that the expression must only find strings that contain characters with alphabetic values (a-z and A-Z). The regular expression may also be used to look for occurrences of particular words within a string, as long as all characters in the searched word are letters.

This type of regex search is extremely powerful and versatile, since it does not depend on any specific language or character encoding; instead it searches on a much more abstract level for any alphabetic character such as those found in English (A-Z) and their associated lowercase equivalents (a-z). Regex letter-only patterns are also useful when dealing with data from more complex languages such as Japanese or Chinese which rely on multiple character encodings to represent written language due to their different scripts.

See more about regex letter only