Manual Pages  — ISALNUM

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

amp;060 ``0''	061 ``1''	062 ``2''	063 ``3''	064 ``4''
amp;065 ``5''	066 ``6''	067 ``7''	070 ``8''	071 ``9''
amp;101 ``A''	102 ``B''	103 ``C''	104 ``D''	105 ``E''
amp;106 ``F''	107 ``G''	110 ``H''	111 ``I''	112 ``J''
amp;113 ``K''	114 ``L''	115 ``M''	116 ``N''	117 ``O''
amp;120 ``P''	121 ``Q''	122 ``R''	123 ``S''	124 ``T''
amp;125 ``U''	126 ``V''	127 ``W''	130 ``X''	131 ``Y''
amp;132 ``Z''	141 ``a''	142 ``b''	143 ``c''	144 ``d''
amp;145 ``e''	146 ``f''	147 ``g''	150 ``h''	151 ``i''
amp;152 ``j''	153 ``k''	154 ``l''	155 ``m''	156 ``n''
amp;157 ``o''	160 ``p''	161 ``q''	162 ``r''	163 ``s''
amp;164 ``t''	165 ``u''	166 ``v''	167 ``w''	170 ``x''
amp;171 ``y''	172 ``z''	amp;	amp;	amp;

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