50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
/*
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FUNCTION
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<<isalpha>>, <<isalpha_l>>---alphabetic character predicate
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INDEX
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isalpha
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INDEX
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isalpha_l
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SYNOPSIS
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#include <ctype.h>
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int isalpha(int <[c]>);
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#include <ctype.h>
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int isalpha_l(int <[c]>, locale_t <[locale]>);
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DESCRIPTION
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<<isalpha>> is a macro which classifies singlebyte charset values by table
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lookup. It is a predicate returning non-zero when <[c]> represents an
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alphabetic ASCII character, and 0 otherwise. It is defined only if
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<[c]> is representable as an unsigned char or if <[c]> is EOF.
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<<isalpha_l>> is like <<isalpha>> but performs the check based on the
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locale specified by the locale object locale. If <[locale]> is
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LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
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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 isalpha>>' or `<<#undef isalpha_l>>'.
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RETURNS
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<<isalpha>>, <<isalpha_l>> return non-zero if <[c]> is a letter.
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PORTABILITY
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<<isalpha>> is ANSI C.
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<<isalpha_l>> is POSIX-1.2008.
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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 isalpha
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int
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isalpha (int c)
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{
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return(__CTYPE_PTR[c+1] & (_U|_L));
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}
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