Mega Code Archive
Get numeric input facet of the locale loc and read value with numeric input facet
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/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <locale>
#include <iostream>
#include <cstdlib>
#include <iterator>
int main()
{
// create copy of current global locale
std::locale loc;
// iterator to read from standard input
typedef std::istreambuf_iterator<char> InIt;
InIt beg = InIt(std::cin);
InIt end = InIt();
// stream which defines input format
std::ios_base& fmt = std::cin;
// declare output arguments
std::ios_base::iostate err;
float value;
// get numeric input facet of the locale loc
std::num_get<char, InIt> const& ng
= std::use_facet<std::num_get<char, InIt> >(loc);
// read value with numeric input facet
ng.get(beg, end, fmt, err, value);
// print value or error message
if (err == std::ios_base::goodbit) {
std::cout << "value: " << value << '\n';
}
else if (err == std::ios_base::eofbit) {
std::cout << "value: " << value << " (EOF encountered)\n";
}
else if (err & std::ios_base::badbit) {
std::cerr << "fatal error while reading numeric value\n";
return EXIT_FAILURE;
}
else if (err & std::ios_base::failbit) {
std::cerr << "format error while reading numeric value\n";
return EXIT_FAILURE;
}
}
us
format error while reading numeric value
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