Wildcard character
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 shells and Windows PowerShell, ranges of characters enclosed in square brackets ("[" and "]") substitute for all the characters in their ranges; for example, [A-Za-z] substitutes 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 regular expressions, the period (.) is the wildcard character for a single character. Combined with the asterisk operator (.*) it will match any number of characters.
[edit] See also
[edit] References
This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).
