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:
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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)