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Implicit scanning in Icon

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Much of the power of Icon in text analysis comes from the use of implicit scanning. In this technique, a particular string is designated as the current subject of scanning operations. Many of the usual string functions like ``match()'' can easily be used to analyze this subject.

In general, the expression

    e1 ? e2
means to make the string e1 the subject of scanning operations within expression e2. Within expression e2, you can call the common string functions like ``any()'' and ``find()'' and omit their second arguments. These functions will implicitly use the current subject as their second argument.

For example, this expression

    "syzygy" ? ( every write ( find ( "y" ) ) );
will produce the same result as
    every write ( find "y", "syzygy" );

See also: Text processing in Icon
Previous: Using strings in Icon
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John Shipman,
Last updated: 1996/01/06 21:12:57 UT
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