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Regex for first word

Regex for first word

A word 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 word and how regex can be matched for a given first word.

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

The word should have the following criteria and structure-

  • one or more words with separated by space
  • the first word should be a valid word

Regex for matching the first word in a sentence

Regular Expression for first word-


Test string examples for the above regex-

Input StringMatch Output
Hello WorldHello
The world is a nice placeThe

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

Here is a detailed explanation of the above regex-


^ asserts position at start of a line
1st Capturing Group ([\w\-]+)
Match a single character present in the list below [\w\-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
\- matches the character - with index 4510 (2D16 or 558) 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 the first word in a sentence.