Re: libstdc++-v3 HOWTO: Chapter 22

[Simon Whomsley <whomsley at avacadcam dot com>]

There is a bug in the Toupper example code 'http://gcc.gnu.org/onlinedocs/libstdc++/22_locale/howto.html'. In it, when constructing Toupper (in main***), the 'std::local("C")' is destructed immediately after the 'up'  is constructed causing 'up::loc' reference to be invalid when std::transform is called. (dito Tolower..)

Simon

  #include <iterator>    // for back_inserter
#include <locale>
#include <string>
#include <algorithm>
#include <cctype>      // old <ctype.h>

struct Toupper
{
Toupper (std::locale const& l) : loc(l) {;}
char operator() (char c)  { return std::toupper(c,loc); }
private:
std::locale const& loc;
};


struct Tolower
{
Tolower (std::locale const& l) : loc(l) {;}
char operator() (char c)  { return std::tolower(c,loc); }
private:
std::locale const& loc;
};


int main ()
{
std::string  s ("Some Kind Of Initial Input Goes Here");
Toupper      up   ( std::locale("C") );	// ***
Tolower      down ( std::locale("C") );


// Change everything into upper case
std::transform (s.begin(), s.end(), s.begin(),
up
);


// Change everything into lower case
std::transform (s.begin(), s.end(), s.begin(),
down
);


// Change everything back into upper case, but store the
// result in a different string
std::string  capital_s;
std::transform (s.begin(), s.end(), std::back_inserter(capital_s),
up
);
}