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

Header: <string>

Behaves as a FormattedOutputFunction. After constructing and checking the sentry object, determines the output format padding. 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. Equivalent to return os « std::basic_string_view<CharT, Traits>(str);. (since C++17)

# Declarations

template< class CharT, class Traits, class Allocator >
std::basic_ostream<CharT, Traits>&
operator<<( std::basic_ostream<CharT, Traits>& os,
const std::basic_string<CharT, Traits, Allocator>& str );

template< class CharT, class Traits, class Allocator >
std::basic_istream<CharT, Traits>&
operator>>( std::basic_istream<CharT, Traits>& is,
std::basic_string<CharT, Traits, Allocator>& str );

# Parameters

os: a character output stream
is: a character input stream
str: the string to be inserted or extracted

# Example

#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';
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 25	C++98	n was the smaller of os.width() and str.size()	n is the larger of them
LWG 90	C++98	std::isspace(c, getloc()) was used to checkfor spaces, but getloc is not declared in	replaced getloc()with is.getloc()
LWG 91	C++98	operator» did not behaveas a FormattedInputFunction	behaves as aFormattedInputFunction
LWG 211	C++98	operator» did not set failbit if no character is extracted	sets failbit
LWG 435	C++98	characters were inserted by os.rdbuf()->sputn(str.data(), n),and the resolution of LWG issue 25 made the behaviorundefined if os.width() is larger than str.size()	determines the paddingfirst and inserts the paddedcharacter sequence instead
LWG 586	C++98	operator« did not behaveas a FormattedOutputFunction	behaves as aFormattedOutputFunction

# See also

operator«