function template
<locale>

std::isdigit

template <class charT>
  bool isdigit (charT c, const locale& loc);
Check if character is a decimal digit using locale
Checks whether c is a decimal digit character using the ctype facet of locale loc, returning the same as if ctype::is is called as:

 
 
use_facet < ctype<charT> > (loc).is (ctype_base::digit, c)


This function template overloads the C function isdigit (defined in <cctype>).

Parameters

c
Character to be checked.
loc
Locale to be used. It shall have a ctype facet.

The template argument charT is the character type.

Return Value

true if indeed c is a decimal digit character.
false otherwise.

Example

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// isdigit example (C++)
#include <iostream>       // std::cout
#include <string>         // std::string
#include <locale>         // std::locale, std::isdigit
#include <sstream>        // std::stringstream

int main ()
{
  std::locale loc;
  std::string str="1776ad";
  if (isdigit(str[0],loc))
  {
    int year;
    std::stringstream(str) >> year;
    std::cout << "The year that followed " << year << " was " << (year+1) << ".\n";
  }
  return 0;
}


Output:

The year that followed 1776 was 1777.

Data races

Both loc and its ctype facet are accessed.

Exception safety

Strong guarantee: if an exception is thrown, there are no effects.

See also

ctype
Character type facet (class template )
isdigit (cctype)
Check if character is decimal digit (function )
isalnum
Check if character is alphanumeric using locale (function template )
isalpha
Check if character is alphabetic using locale (function template )

C++