isdigit, iswdigit, _ismbcdigit

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Header File

ctype.h, mbstring.h

Category

Classification Routines

Prototype

int isdigit(int c);

int iswdigit(wint_t c);

int _ismbcdigit(unsigned int c);

Description

Tests for decimal-digit character.

isdigit is a macro that classifies ASCII-coded integer values by table lookup. The macro is affected by the current locale's LC_CTYPE category. For the default C locale, c is a digit (0 to 9).

You can make this macro available as a function by undefining (#undef) it.

Return Value

isdigit returns nonzero if c is a digit.

_ismbcdigit returns true if and only if the argument c is a single-byte representation of an ASCII digit.

Example

#include <stdio.h>
#include <ctype.h>
int main(void)
{
  char c = 'C';
  if (isdigit(c))
    printf("%c is a digit\n",c);
  else
    printf("%c is not a digit\n",c);
  return 0;
}

Portability

	POSIX	Win32	ANSI C	ANSI C++
isdigit	+	+	+	+
_ismbcdigit		+
iswdigit		+	+	+