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isdigit, iswdigit, _ismbcdigit

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

Copy Code

    #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 |  | + | + | +

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