std::ws

From Cppreference

Discards leading whitespace from an input stream.

First, constructs a std::basic_istream::sentry object with noskipws set to true. Afterwards, if good()==false, calls setstate(failbit) and returns. Otherwise, extracts characters from the stream and discards them until any one of the following conditions occurs:

• end of file condition occurs in the input sequence (in which case the function calls setstate(eofbit) but does not set failbit.

• the next available character c in the input sequence is not whitespace as determined by std::isspace(c, is.getloc()). The non-whitespace character is not extracted.

This is an input-only I/O manipulator, it may be called with an expression such as in << std::ws for any in of type std::basic_istream.

[edit] Parameters

[edit] Return value

is (reference to the stream after extraction of consecutive whitespace)

[edit] Example

#include <iostream>
#include <sstream>
int main()
{
    std::istringstream s("     this is a test");
    std::string line;
    s >> std::ws;
    getline(s, line);
    std::cout << "ws + getline returns: \"" << line << "\"\n";
}

Output:

ws + getline returns: "this is a test"

[edit] See also