toascii() - convert a byte to 7-bit ASCII
#include <ctype.h>
int toascii (int c)
The toascii(3) function strips all but the low 7 bits from a letter, including parity or other marker bits.
The toascii(3) function always returns a valid ASCII character.
isascii(3)
isalnum(3)
isalpha(3)
iscntrl(3)
isdigit(3)
isgraph(3)
islower(3)
isprint(3)
ispunct(3)
isspace(3)
isupper(3)
isxdigit(3)
tolower(3)
toupper(3)