isdigit, iswdigit, _isdigit_l, _iswdigit_l

Determines whether an integer represents a decimal-digit character.

int isdigit(
   int c
);
int iswdigit(
   wint_t c
);
int _isdigit_l(
   int c,
   _locale_t locale
);
int _iswdigit_l(
   wint_t c,
   _locale_t locale
);

c
Integer to test.

locale
The locale to use.

Each of these routines returns nonzero if c is a particular representation of a decimal-digit character. isdigit returns a nonzero value if c is a decimal digit (0 - 9). iswdigit returns a nonzero value if c is a wide character that corresponds to a decimal-digit character. Each of these routines returns 0 if c doesn't satisfy the test condition.

The versions of these functions that have the _l suffix use the locale that's passed in instead of the current locale for their locale-dependent behavior. For more information, see Locale.

The behavior of isdigit and _isdigit_l is undefined if c isn't EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c isn't one of these values, the functions raise an assertion.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

For more compatibility information, see Compatibility.

Character classification
Locale
is, isw routines