isdigit - test for decimal digit

Syntax

#include <ctype.h> int isdigit(int c);

Description isdigit() whether the character c is a decimal digit.

	In all cases, the argument c is an int, the value of which must be representable as an unsigned char or must equal the value of the macro EOF. If the argument c has any other value, the behavior is undefined.
Return val.	!= 0 0	Decimal digit Not a decimal digit
Notes	isdigit() is implemented both as a function and as a macro. To generate a function call, the definition of the macro name must be first undefined (#undef isdigit). The behavior of isdigit() is determined by the class digit of the current locale. The current locale is the C locale, unless it was explicitly changed using setlocale().
See also	isalnum(), isalpha(), iscntrl(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit(), ctype.h.