operator<<,>>(std::basic_string)

Then inserts each character from the resulting sequence seq (the contents of str plus padding) to the output stream os as if by calling os.rdbuf()->sputn(seq, n), where n is std::max (os.width(), str.size()) Finally, calls os.width(0) to cancel the effects of std::setw , if any.

• N characters are read, where N is is.width() if is.width() > 0, otherwise N is str.max_size(),
• the end-of-file condition occurs in the stream is, or
• std::isspace (c, is.getloc()) is true for the next character c in is (this whitespace character remains in the input stream).

If no characters are extracted then std::ios::failbit is set on is, which may throw std::ios_base::failure .

#include <iostream>
#include <sstream>
#include <string>
 
int main()
{
 std::string greeting = "Hello, whirled!";
 std::istringstream iss(greeting);
 
 std::string hello_comma, whirled, word;
 
 iss >> hello_comma;
 iss >> whirled;
 
 std::cout << greeting << '\n'
 << hello_comma << '\n' << whirled << '\n';
 
 // Reset the stream
 iss.clear();
 iss.seekg(0);
 
 while (iss >> word)
 std::cout << '+' << word << '\n';
}

Output:

Hello, whirled!
Hello,
whirled!
+Hello,
+whirled!