December 24, 20222 min read

Regex for lowercase letters

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 lowercase letter and how regex can be matched for a given lowercase letter.

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 lowercase letter

The letter should have the following criteria and structure-

  • a lowercase letter is a unit of information that represents a single letter from a-z or A-Z
  • It can contain lowercase letters.

Regex for checking if lowercase letters is valid or not

Regular Expression for lowercase letter-


Test string examples for the above regex-

Input StringMatch Output
12Gdoes not match
ATOZdoes not match
;does not match

Here is a detailed explanation of the above regex-


^ asserts position at start of a line
Match a single alphabet present in the list below [a-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single alphabet in the range between a (index 97) and z (index 122) (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)

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

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About the Author
Satvik is a passionate developer turned Entrepreneur. He is fascinated by JavaScript, Operating System, Deep Learning, AR/VR. He has published several research papers and applied for patents in the field as well. Satvik is a speaker in conferences, meetups talking about Artificial Intelligence, JavaScript and related subjects. His goal is to solve complex problems that people face with automation. Related projects can be seen at - [Projects](/projects)
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