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)
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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; }
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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)