January 8, 20232 min read

Regex for matching upto the first occurance of a character

A character is a unit of information that represents one or more letters i.e., from a-z or A-Z. In this article let's understand how we can create a regex for first character and how regex can be matched for a given first character.

Regex (short for regular expression) is a powerful tool used for searching and manipulating text. It is composed of a sequence of first characters 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 the string

The word should have the following criteria and structure-

  • one or more characters
  • the first character should be a valid character

Regex for matching upto the first occurance of a character

The [^;] is a character class, it matches everything but a semicolon. It matches the whole string until it sees ; character.

Regular Expression for first character-


Test string examples for the above regex-

Input StringMatch Output
Hello; WorldHello
The world; is a nice placeThe world

Here is a detailed explanation of the above regex-


^ asserts position at start of a line
Match a single character not present in the list below [^;]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
; matches the character ; with index 5910 (3B16 or 738) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)

Hope this article was useful to check and match until the first occurance of character in a sentence.

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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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