44 lines
848 B
C
44 lines
848 B
C
/*
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FUNCTION
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<<isdigit>>---decimal digit predicate
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INDEX
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isdigit
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ANSI_SYNOPSIS
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#include <ctype.h>
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int isdigit(int <[c]>);
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TRAD_SYNOPSIS
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#include <ctype.h>
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int isdigit(<[c]>);
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DESCRIPTION
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<<isdigit>> is a macro which classifies ASCII integer values by table
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lookup. It is a predicate returning non-zero for decimal digits, and 0 for
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other characters. It is defined only if <[c]> is representable as an
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unsigned char or if <[c]> is EOF.
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You can use a compiled subroutine instead of the macro definition by
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undefining the macro using `<<#undef isdigit>>'.
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RETURNS
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<<isdigit>> returns non-zero if <[c]> is a decimal digit (<<0>>--<<9>>).
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PORTABILITY
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<<isdigit>> is ANSI C.
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No supporting OS subroutines are required.
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*/
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#include <_ansi.h>
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#include <ctype.h>
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#undef isdigit
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int
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_DEFUN(isdigit,(c),int c)
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{
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return(__ctype_ptr__[c+1] & _N);
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}
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