Wildcard

In computing, a wildcard refers to a character that can be substituted for zero or more characters in a string. Wildcards are commonly used in computer programming, database SQL search queries, and when navigating through DOS or Unix directories via the command prompt.

Below are some popular uses for wildcards:

  • Regular Expressions - A period (.) matches a single character, while .* matches zero or more characters and .+ matches one or more characters.
    ▶ Example: $pattern = "Mac(.*)"
  • SQL Queries - A percent symbol (%) matches zero or more characters, while an underscore (_) matches a single character.
    ▶ Example: SELECT * FROM Computers WHERE Platform LIKE 'Mac%'
  • Directory Navigation - An asterisk (*) matches zero or more characters, while a question mark (?) matches a single character.
    ▶ Example: dir *.exe

In the examples above, wildcards are used to search for partial matches instead of exact matches. This can be helpful when searching for files or looking up information from a database.

Updated May 26, 2010

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