Erase white spaces from stream

[fpiro07]

I input 9X^3 + 5X into a string using the getline() function.

I want to erase the white spaces in order to obtain 9X^3+5X.

I can do that with a simple for-loop but I came about the skipws manipulator. Can I use it here?

[maeriden]

Nope. Stream manipulators work with the extraction and insertion operators. Skipws is set to on by default so you'd be already using it if you used >> or <<

[fpiro07]

So if I write

string temp;
cin >> skipws >> temp;

and I input

" C"

temp becomes

"C"

?

Whereas if I write

string temp;
cin >> skipws;
cin.getline(temp);

and I input the same string temp becomes

" C"

?

[Cubbi]

To swallow the leading whitespace before an unformatted input function such as getline(), you want to use ws, not skipws.

cin >> ws;
getline(cin, temp);

Formatted input functions, such as operator>>, do it automatically *unless* you use noskipws. Skipws just reaffirms the default settings.

I don't see how that helps you solve your original task of removing whitespace from a string. Just erase-remove:

#include <iostream>
#include <string>
#include <algorithm>
int main()
{
    std::string s = "9X^3 + 5X";
    s.erase( std::remove(s.begin(), s.end(), ' '), s.end());
    std::cout << s << '\n';
}

or even simpler

#include <iostream>
#include <string>
#include <boost/algorithm/string/erase.hpp>

int main()
{
    std::string s = "9X^3 + 5X";
    boost::erase_all(s, " ");
    std::cout << s << '\n';
}

demo: http://ideone.com/ek7Owy