Wildcardmerkkien

Wildcardmerkkien, also known as wildcard characters, are pattern-matching symbols used in computing to represent one or more unspecified characters in a string. They are employed to broaden searches, filter lists, and match filenames or data records when exact strings are not known. Different systems implement wildcarding in slightly different ways, but the underlying idea is to substitute uncertain parts of a string with a placeholder.

The most common wildcard characters are the asterisk (*) which matches any sequence of characters, including none; the question mark (?) which matches exactly one character; and square brackets use for character classes, such as [abc] which matches any of a, b, or c. In SQL and some data-query languages, the percent sign (%) matches any sequence of characters and the underscore (_) matches a single character. Some environments also support ranges and negation inside brackets, such as [a-z] or [^0-9]. Extended globbing in certain shells adds further operators to refine matches.

Usage contexts include file systems and shells, databases, and search tools. In file systems, glob patterns are used for matching files, for example, in Unix-like shells: ls report* lists files starting with report, while in Windows, dir *.txt lists text files. In SQL, the LIKE operator uses % and _ to shape matches, e.g., WHERE name LIKE 'A%' finds names starting with A. Programmatic libraries often provide globbing utilities or translate wildcard patterns into more formal regular expressions.

Escaping and literal matching depend on the environment. Characters that carry wildcard meaning can usually be escaped with a backslash, quotes, or environment-specific escape rules to treat them as ordinary characters.