asciiXdigitValue
Determines the numeric value of a character as a hexadecimal digit. If the character is not a hex digit according to func@GLib.ascii_isxdigit, -1
is returned.
Differs from func@GLib.unichar_xdigit_value because it takes a char, so there's no worry about sign extension if characters are signed.
Differs from func@GLib.unichar_xdigit_value because it takes a char, so there's no worry about sign extension if characters are signed.
Return
the numerical value of @c if it is a hex digit, -1
otherwise
Parameters
c
an ASCII character