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Regex for one alphabet

Regex for one alphabet

An alphabet is a unit of information that represents a single letter i.e., from a-z or A-Z. In this article let's understand how we can create a regex for alphabet and how regex can be matched for a given alphabet.

Regex (short for regular expression) is a powerful tool used for searching and manipulating text. It is composed of a sequence of alphabets that define a search pattern. Regex can be used to find patterns in large amounts of text, validate user input, and manipulate strings. It is widely used in programming languages, text editors, and command line tools.

Structure of a alphabet

The alphabet should have the following criteria and structure-

  • an alphabet is a unit of information that represents a single letter from a-z or A-Z

Regex for checking if one alphabet is valid or not

Regular Expression for alphabet-

/^[a-z]$/igm

Test string examples for the above regex-

Input StringMatch Output
aedoes not match
12Gdoes not match
qmatches
Amatches
zmatches

Note the i modifier in the regex takes care of the UPPERCASE letters.

Here is a detailed explanation of the above regex-

/^[a-z]$/igm

^ asserts position at start of a line
Match a single character present in the list below [a-zA-Z]
a-z matches a single character in the range between a (index 97) and z (index 122) (case insensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case insensitive)
$ asserts position at the end of a line
Global pattern flags
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
g modifier: global. All matches (don't return after first match)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

Hope this article was useful to check if the string is a valid single alphabet or not.