function template
<locale>

std::isalnum

template <class charT>
  bool isalnum (charT c, const locale& loc);
Check if character is alphanumeric using locale
Checks whether c is an alphanumeric 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::alnum, c)


This function template overloads the C function isalnum (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 an alphanumeric character.
false otherwise.

Example

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

int main ()
{
  std::locale loc;
  std::string str = "c3po...";
  std::string::size_type i=0;
  while ( (i<str.length()) && (std::isalnum(str[i])) ) {++i;}
  std::cout << "The first " << i << " characters are alphanumeric.\n";
  return 0;
}


Output:

The first 4 characters are alphanumeric.

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 )
isalnum (cctype)
Check if character is alphanumeric (function )
isalpha
Check if character is alphabetic using locale (function template )
isdigit
Check if character is a decimal digit using locale (function template )

C++