freebsd man page for isalpha

ISALPHA(3)						   BSD Library Functions Manual 						ISALPHA(3)

NAME
     isalpha -- alphabetic character test

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <ctype.h>

     int
     isalpha(int c);

     int
     isalpha_l(int c, locale_t loc);

DESCRIPTION
     The isalpha() function tests for any character for which isupper(3) or islower(3) is true.  The value of the argument must be representable
     as an unsigned char or the value of EOF.

     In the ASCII character set, this includes the following characters (with their numeric values shown in octal):

     101 ``A''	   102 ``B''	 103 ``C''     104 ``D''     105 ``E''
     106 ``F''	   107 ``G''	 110 ``H''     111 ``I''     112 ``J''
     113 ``K''	   114 ``L''	 115 ``M''     116 ``N''     117 ``O''
     120 ``P''	   121 ``Q''	 122 ``R''     123 ``S''     124 ``T''
     125 ``U''	   126 ``V''	 127 ``W''     130 ``X''     131 ``Y''
     132 ``Z''	   141 ``a''	 142 ``b''     143 ``c''     144 ``d''
     145 ``e''	   146 ``f''	 147 ``g''     150 ``h''     151 ``i''
     152 ``j''	   153 ``k''	 154 ``l''     155 ``m''     156 ``n''
     157 ``o''	   160 ``p''	 161 ``q''     162 ``r''     163 ``s''
     164 ``t''	   165 ``u''	 166 ``v''     167 ``w''     170 ``x''
     171 ``y''	   172 ``z''

     The isalpha_l() function takes an explicit locale argument, whereas the isalpha() function uses the current global or per-thread locale.

RETURN VALUES
     The isalpha() function returns zero if the character tests false and returns non-zero if the character tests true.

COMPATIBILITY
     The 4.4BSD extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered
     obsolete and may not be supported in future releases.  The iswalpha() function should be used instead.

SEE ALSO
     ctype(3), islower(3), isupper(3), iswalpha(3), xlocale(3), ascii(7)

STANDARDS
     The isalpha() function conforms to ISO/IEC 9899:1990 (``ISO C90'').  The isalpha_l() function conforms to IEEE Std 1003.1-2008 (``POSIX.1'').

BSD
								   July 17, 2005							       BSD