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