NAME
isdigit, isnumber – decimal-digit character test
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <ctype.h>
int
isdigit(int c);
int
isnumber(int c);
DESCRIPTION
The isdigit() function tests for a decimal digit character. Regardless of locale, this includes the following characters only:
| ``0'' ``1'' ``2'' ``3'' ``4'' |
| ``5'' ``6'' ``7'' ``8'' ``9'' |
The isnumber() function behaves similarly to isdigit(), but may recognize additional characters, depending on the current locale setting.
The value of the argument must be representable as an unsigned char or the value of EOF.
RETURN VALUES
The isdigit() and isnumber() functions return zero if the character tests false and return non-zero if the character tests true.
COMPATIBILITY
The 4.4BSD extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered obsolete and may not be supported in future releases. The iswdigit() function should be used instead.
SEE ALSO
STANDARDS
The isdigit() function conforms to ISO/IEC 9899:1990 (“ISO C90”).
HISTORY
The isnumber() function appeared in 4.4BSD.