Regex
regex
December 24, 20222 min read

Regex for uppercase 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 uppercase letter and how regex can be matched for a given uppercase 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 uppercase letter

The string should have the following criteria and structure-

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

Regex for checking if uppercase letters is valid or not

Regular Expression for uppercase letter-

/^[A-Z]+$/gm

Test string examples for the above regex-

Input StringMatch Output
PINCODEmatches
12Gdoes not match
hellodoes not match
ATOZmatches
;does not match

Here is a detailed explanation of the above regex-

/^[A-Z]+$/gm

^ 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 uppercase letters or not.

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About the Author
Satvik
Satvik
Entrepreneur
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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