CTYPE(3) CTYPE(3) NAME isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, toupper, tolower, toascii - character classification macros SYNOPSIS #include isalpha(c) . . . DESCRIPTION These macros classify ASCII-coded integer values by table lookup. Each is a predicate returning nonzero for true, zero for false. _I_s_a_s_c_i_i and _t_o_a_s_c_i_i are defined on all integer values; the rest are defined only where _i_s_a_s_c_i_i is true and on the single non-ASCII value EOF (see _s_t_d_i_o(3S)). _i_s_a_l_p_h_a _c is a letter _i_s_u_p_p_e_r _c is an upper case letter _i_s_l_o_w_e_r _c is a lower case letter _i_s_d_i_g_i_t _c is a digit _i_s_x_d_i_g_i_t _c is a hex digit _i_s_a_l_n_u_m _c is an alphanumeric character _i_s_s_p_a_c_e _c is a space, tab, carriage return, newline, vertical tab, or formfeed _i_s_p_u_n_c_t _c is a punctuation character (neither control nor alphanumeric) _i_s_p_r_i_n_t _c is a printing character, code 040(8) (space) through 0176 (tilde) _i_s_g_r_a_p_h _c is a printing character, similar to _i_s_p_r_i_n_t except false for space. _i_s_c_n_t_r_l _c is a delete character (0177) or ordinary control char‐ acter (less than 040). _i_s_a_s_c_i_i _c is an ASCII character, code less than 0200 _t_o_l_o_w_e_r _c is converted to lower case. Return value is undefined if not _i_s_u_p_p_e_r_(_c_)_. _t_o_u_p_p_e_r _c is converted to upper case. Return value is undefined if not _i_s_l_o_w_e_r_(_c_)_. _t_o_a_s_c_i_i _c is converted to be a valid ascii character. SEE ALSO ascii(7) 7th Edition May 12, 1986 CTYPE(3)