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 any decimal-digit character. For any locale, this includes the following characters only:

``0''

``1'' ``2'' ``3'' ``4''

``5''

``6'' ``7'' ``8'' ``9''

For single C chars locales (see multibyte(3) ) the value of the argument is representable as an unsigned char or the value of EOF.

Return Values

The isdigit() function returns zero if the character tests false and returns non-zero if the character tests true.

Compatibility

Although isdigit() accepts arguments outside of the range of the unsigned char type in locales with large character sets, this is a 4.4BSD extension and the iswdigit() function should be used instead for maximum portability.

See Also

ctype(3) , iswdigit(3) , multibyte(3) , ascii(7)

Standards

The isdigit() function conforms to ISO/IEC 9899:1990 (``ISO C89'').

Table of Contents

• Name
• Library
• Synopsis
• Description
• Return Values
• Compatibility
• See Also
• Standards