Wildcard character
From Wikipedia, the free encyclopedia
- For other meanings of 'wild card' see wild card.
The term wildcard character has the following meanings:
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[edit] Telecommunication
In telecommunications, a wildcard character is a character that may be substituted for any of a defined subset of all possible characters.
- In high-frequency (HF) radio automatic link establishment, the wildcard character "?" may be substituted for any one of the 36 characters, "A" through "Z" and "0" through "9."
- Whether the wildcard character represents a single character or a string of characters must be specified.
[edit] Computing
In computer (software) technology, a wildcard character can be used to substitute for any other character or characters in a string.
[edit] Files and Directories
When specifying file names (or paths) in CP/M, DOS, Microsoft Windows and Unix-like operating systems, the asterisk character("*") substitutes for any zero or more characters, and the question mark (?) substitutes for any one character. In Unix-like operating systems, a ranges of characters in square brackets substitute for all the characters in their range, such as [A-Za-z] can substitute for any single capitalized or lowercase letter. Matching wildcard patterns to multiple files or paths is referred to as glob expansion.
[edit] Databases
In SQL, wildcard characters can be used in "LIKE" expressions; the percent sign (%) matches zero or more characters, and underscore (_) a single character. In Microsoft Access, wildcard characters can be used in "LIKE" expressions; the asterisk sign (*) matches zero or more characters, and question mark (?) a single character.
[edit] Regular Expressions
In many regular expression implementations, the period (.) is the wildcard character for a single character.
[edit] References
This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).
