std::ctype<char>
| Defined in header  <locale> | ||
| template<> class ctype<char>; | ||
This specialization of std::ctype encapsulates character classification features for type char. Unlike general-purpose std::ctype, which uses virtual functions, this specialization uses table lookup to classify characters (which is generally faster).
The base class std::ctype<char> implements character classification equivalent to the minimal "C" locale. The classification rules can be extended or modified if constructed with a non-default classification table argument, if constructed as std::ctype_byname<char> or as a user-defined derived facet. All std::istream formatted input functions are required to use std::ctype<char> for character classing during input parsing.
| Contents | 
[edit] Member types
| Member type | Definition | 
| char_type | char | 
[edit] Member functions
| constructs a new std::ctype<char> facet (public member function) | |
| destructs a std::ctype<char> facet (protected member function) | |
| obtains the character classification table (public member function) | |
| [static] | obtains the "C" locale character classification table (public static member function) | 
| classifies a character or a character sequence, using the classification table (public member function) | |
| locates the first character in a sequence that conforms to given classification, using the classification table (public member function) | |
| locates the first character in a sequence that fails given classification, using the classification table (public member function) | |
| invokes do_toupper(public member function of std::ctype) | |
| invokes do_tolower(public member function of std::ctype) | |
| invokes do_widen(public member function of std::ctype) | |
| invokes do_narrow(public member function of std::ctype) | 
[edit] Protected member functions
| [virtual] | converts a character or characters to uppercase (virtual protected member function of std::ctype) | 
| [virtual] | converts a character or characters to lowercase (virtual protected member function of std::ctype) | 
| [virtual] | converts a character or characters from chartocharT(virtual protected member function of std::ctype) | 
| [virtual] | converts a character or characters from charTtochar(virtual protected member function of std::ctype) | 
[edit] Member objects
| static std::locale::id id [static] | id of the locale (public static member constant) | 
| static const std::size_t  table_size [static] | size of the classification table, at least 256 (public static member constant) | 
Inherited from std::ctype_base
Member types
| Type | Definition | 
| mask | unspecified bitmask type (enumeration, integer type, or bitset) | 
Member constants
| space [static] | the value of maskidentifying whitespace character classification(public static member constant) | 
| print [static] | the value of maskidentifying printable character classification(public static member constant) | 
| cntrl [static] | the value of maskidentifying control character classification(public static member constant) | 
| upper [static] | the value of maskidentifying uppercase character classification(public static member constant) | 
| lower [static] | the value of maskidentifying lowercase character classification(public static member constant) | 
| alpha [static] | the value of maskidentifying alphabetic character classification(public static member constant) | 
| digit [static] | the value of maskidentifying digit character classification(public static member constant) | 
| punct [static] | the value of maskidentifying punctuation character classification(public static member constant) | 
| xdigit [static] | the value of maskidentifying hexadecimal digit character classification(public static member constant) | 
| blank [static] (C++11) | the value of maskidentifying blank character classification(public static member constant) | 
| alnum [static] | alpha | digit (public static member constant) | 
| graph [static] | alnum | punct (public static member constant) | 
[edit] Example
The following example demonstrates modification of ctype<char> to tokenize comma-separated values
#include <iostream> #include <vector> #include <locale> #include <sstream> // This ctype facet classifies commas and endlines as whitespace struct csv_whitespace : std::ctype<char> { static const mask* make_table() { // make a copy of the "C" locale table static std::vector<mask> v(classic_table(), classic_table() + table_size); v[','] |= space; // comma will be classified as whitespace v[' '] &= ~space; // space will not be classified as whitespace return &v[0]; } csv_whitespace(std::size_t refs = 0) : ctype(make_table(), false, refs) {} }; int main() { std::string in = "Column 1,Column 2,Column 3\n123,456,789"; std::string token; std::cout << "default locale:\n"; std::istringstream s1(in); while(s1 >> token) std::cout << " " << token << '\n'; std::cout << "locale with modified ctype:\n"; std::istringstream s2(in); s2.imbue(std::locale(s2.getloc(), new csv_whitespace)); while(s2 >> token) std::cout << " " << token<< '\n'; }
Output:
default locale: Column 1,Column 2,Column 3 123,456,789 locale with modified ctype: Column 1 Column 2 Column 3 123 456 789
[edit] See also
| defines character classification tables (class template) | |
| defines character classification categories (class template) | |
| creates a ctype facet for the named locale (class template) | 



