The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <string>
#include <iostream>
#include <algorithm>
#include <iterator>
#include <locale>
using namespace std;
int main()
{
string input;
// don't skip leading whitespaces
cin.unsetf (ios::skipws);
// read all characters while compressing whitespaces
const locale& loc(cin.getloc()); // locale
unique_copy(istream_iterator<char>(cin), // beginning of source
istream_iterator<char>(), // end of source
back_inserter(input), // destination
[=] (char c1, char c2) { // criterion for adj. duplicates
return isspace(c1,loc) && isspace(c2,loc);
});
// process input
// - here: write it to the standard output
cout << input;
}