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Determines whether an integer represents a decimal-digit character.

Syntax

Isdigit and isxdigit are the only standard narrow character classification functions that are not affected by the currently installed C locale. Although some implementations (e.g. Microsoft in 1252 codepage) may classify additional single-byte characters as digits. Checks whether c is either a decimal digit or an uppercase or lowercase letter. The result is true if either isalpha or isdigit would also return true. Notice that what is considered a letter may depend on the locale being used; In the default 'C' locale, what constitutes a letter is.

Parameters

c
Integer to test.

locale
The locale to use.

C Programming Isdigit

Return Value

Python String Isdigit

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 does not 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 is not EOF or in the range 0 through 0xFF, inclusive. When a debug CRT library is used and c is not one of these values, the functions raise an assertion.

Generic-Text Routine Mappings

Remarks

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

Requirements

For additional compatibility information, see Compatibility.

See also

Isdigit C++ Int

Character Classification
Locale
is, isw Routines