ctype_base ctype...
A facet that includes character classification facilities.
| Member Functions | ||
| do_is() do_narrow() do_scan_is() do_scan_not() do_tolower() do_toupper() |
do_widen() is() narrow() scan_is() scan_not() tolower() |
toupper() widen() |
#include <locale> class ctype_base; template <class charT> class ctype;
class ctype<char>;
ctype<charT> is a facet that allows you to classify characters and perform simple conversions. ctype<charT> also converts upper to lower and lower to upper case, and converts between charT and char. ctype<charT> relies on ctype_base for a set of masks that identify the various classes of characters. These classes are:
The masks are passed to member functions of ctype to obtain the classifications of a character or range of characters.
class ctype_base {
public:
enum mask {
space, print, cntrl, upper, lower,
alpha, digit, punct, xdigit,
alnum=alpha|digit, graph
};
};
template <class charT>
class ctype : public locale::facet, public ctype_base {
public:
typedef charT char_type;
explicit ctype(size_t refs = 0);
bool is(mask, charT) const;
const charT* is(const charT*,
const charT*, mask*) const;
const charT* scan_is(mask, const charT*,
const charT*) const;
const charT* scan_not(mask, const charT*,
const charT*) const;
charT toupper(charT) const;
const charT* toupper(charT*, const charT*) const;
charT tolower(charT) const;
const charT* tolower(charT*, const charT*) const;
charT widen(char) const;
const char* widen(const char*,
const char*, charT*) const;
char narrow(charT, char) const;
const charT* narrow(const charT*, const charT*,
char, char*) const;
static locale::id id;
protected:
~ctype(); // virtual
virtual bool do_is(mask, charT) const;
virtual const charT* do_is(const charT*,
const charT*,
mask*) const;
virtual const charT* do_scan_is(mask,
const charT*,
const charT*) const;
virtual const charT* do_scan_not(mask,
const charT*,
const charT*) const;
virtual charT do_toupper(charT) const;
virtual const charT* do_toupper(charT*,
const charT*) const;
virtual charT do_tolower(charT) const;
virtual const charT* do_tolower(charT*,
const charT*) const;
virtual charT do_widen(char) const;
virtual const char* do_widen(const char*,
const char*,
charT*) const;
virtual char do_narrow(charT, char) const;
virtual const charT* do_narrow(const charT*,
const charT*,
char, char*) const;
};
char_type
Type of character the facet is instantiated on.
explicit ctype(size_t refs = 0)
Construct a ctype facet. If the refs argument is 0, then destruction of the object is delegated to the locale, or locales, containing it. This allows the user to ignore lifetime management issues. On the other hand, if refs is 1, then the object must be explicitly deleted; the locale does not do so.
~ctype(); // virtual and protected
Destroy the facet.
The public members of the ctype facet include an interface to protected members. Each public member xxx has a corresponding virtual protected member do_xxx. All work is delegated to these protected members. For instance, the public widen function simply calls its protected cousin do_widen.
bool is(mask m, charT c) const; const charT* is(const charT* low, const charT* high, mask* vec) const;
Returns do_is(m,c) or do_is(low,high,vec).
char
narrow(charT c, char dfault) const;
const charT*
narrow(const charT* low, const charT*, char dfault,
char* to) const;
Returns do_narrow(c,dfault) or do_narrow(low,high,dfault,to).
const charT* scan_is(mask m, const charT*, const charT* high) const;
Returns do_scan_is(m,low,high).
const charT* scan_not(mask m, const charT* low, const charT* high) const;
Returns do_scan_not(m,low,high).
charT tolower(charT c) const; const charT* tolower(charT* low, const charT* high) const;
Returns do_tolower(c) or do_tolower(low,high).
charT toupper(charT) const; const charT* toupper(charT* low, const charT* high) const;
Returns do_toupper(c) or do_toupper(low,high).
charT widen(char c) const; const char* widen(const char* low, const char* high, charT* to) const;
Returns do_widen(c) or do_widen(low,high,to).
static locale::id id;
Unique identifier for this type of facet.
virtual bool do_is(mask m, charT c) const;
Returns true if c matches the classification indicated by the mask m, where m is one of the values available from ctype_base. For instance, the following call returns true since `a' is an alphabetic character:
ctype<char>().is(ctype_base::alpha,'a');
See ctype_base for a description of the masks.
virtual const charT*
do_is(const charT* low, const charT* high,
mask* vec) const;
Fills vec with every mask from ctype_base that applies to the range of characters indicated by [low,high). See ctype_base for a description of the masks. For instance, after the following call, the first five entries in the array v would each contain the mask value: alpha|lower|print|alnum|graph:
char a[] = "abcde"; ctype_base::mask v[12]; ctype<char>().is(a,a+5,v);
Returns high.
virtual char do_narrow(charT, char dfault) const;
Returns the appropriate char representation for c, if such exists. Otherwise do_narrow returns dfault.
virtual const charT*
do_narrow(const charT* low, const charT* high,
char dfault, char* dest) const;
Converts each character in the range [low,high) to its char representation, if such exists. If a char representation is not available, then the character is converted to dfault. Returns high.
virtual const charT* do_scan_is(mask m, const charT* low, const charT* high) const;
Finds the first character in the range [low,high) that matches the classification indicated by the mask m.
virtual const charT* do_scan_not(mask m, const charT* low, const charT* high) const;
Finds the first character in the range [low,high) that does not match the classification indicated by the mask m.
virtual charT do_tolower(charT) const;
Returns the lower case representation of c, if such exists. Otherwise returns c.
virtual const charT* do_tolower(charT* low, const charT* high) const;
Converts each character in the range [low,high) to its lower case representation, if such exists. If a lower case representation does not exist, then the character is not changed. Returns high.
virtual charT do_toupper(charT c) const;
Returns the upper case representation of c, if such exists. Otherwise returns c.
virtual const charT* do_toupper(charT* low, const charT* high) const;
Converts each character in the range [low,high) to its upper case representation, if such exists. If an upper case representation does not exist, then the character is not changed. Returns high.
virtual charT do_widen(char c) const;
Returns the appropriate charT representation for c.
virtual const char* do_widen(const char* low, const char* high, charT* dest) const;
Converts each character in the range [low,high) to its charT representation. Returns high.
//
// ctype.cpp
//
#include <iostream>
int main ()
{
using namespace std;
locale loc;
string s1("blues Power");
// Get a reference to the ctype<char> facet
const ctype<char>& ct =
#ifndef _RWSTD_NO_TEMPLATE_ON_RETURN_TYPE
use_facet<ctype<char> >(loc);
#else
use_facet(loc,(ctype<char>*)0);
#endif
// Check the classification of the 'a' character
cout << ct.is(ctype_base::alpha,'a') << endl;
cout << ct.is(ctype_base::punct,'a') << endl;
// Scan for the first upper case character
cout << (char)*(ct.scan_is(ctype_base::upper,
s1.begin(),s1.end())) << endl;
// Convert characters to upper case
ct.toupper(s1.begin(),s1.end());
cout << s1 << endl;
return 0;
}
locale, facets, collate, ctype<char>, ctype_byname