operator>>(std::basic_istream)
<istream>
basic_istream<CharT, Traits>&
operator>>( basic_istream<CharT, Traits>& st, CharT& ch );
template< class Traits >
basic_istream<char, Traits>&
operator>>( basic_istream<char, Traits>& st, signed char& ch );
template< class Traits >
basic_istream<char, Traits>&
basic_istream<CharT, Traits>&
operator>>( basic_istream<CharT, Traits>& st, CharT* s );
template< class Traits >
basic_istream<char, Traits>&
operator>>( basic_istream<char, Traits>& st, signed char* s );
template< class Traits >
basic_istream<char, Traits>&
basic_istream<CharT, Traits>&
operator>>( basic_istream<CharT, Traits>& st, CharT (&s)[N] );
template< class Traits, std::size_t N >
basic_istream<char, Traits>&
operator>>( basic_istream<char, Traits>& st, signed char (&s)[N] );
template< class Traits, std::size_t N >
basic_istream<char, Traits>&
Istream&&
ch
. If no character is available, sets failbit (in addition to eofbit that is set as required of a FormattedInputFunction).s
. The extraction stops if any of the following conditions is met:
- A whitespace character (as determined by the ctype<CharT> facet) is found. The whitespace character is not extracted.
- If st.width() is greater than zero, st.width() - 1 characters are stored.
- n - 1 characters are stored, where n is defined as follows:
- If st.width() is greater than zero, std::min (std::size_t (st.width()), N);
- otherwise, n is N.
- End of file occurs in the input sequence (this also sets eofbit).
Istream
is a class type publicly and unambiguously derived from std::ios_base .[edit] Notes
Extracting a single character that is the last character of the stream does not set eofbit
: this is different from other formatted input functions, such as extracting the last integer with operator>>, but this behavior matches the behavior of std::scanf with "%c" format specifier.
[edit] Parameters
[edit] Return value
[edit] Example
#include <iomanip> #include <iostream> #include <sstream> int main() { std::string input = "n greetings"; std::istringstream stream(input); char c; const int MAX = 6; char cstr[MAX]; stream >> c >> std::setw (MAX) >> cstr; std::cout << "c = " << c << '\n' << "cstr = " << cstr << '\n'; double f; std::istringstream ("1.23") >> f; // rvalue stream extraction std::cout << "f = " << f << '\n'; }
Output:
c = n cstr = greet f = 1.23
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 13 | C++98 | the definition of n mentioned a non-existing name eos | replaced with CharT() |
LWG 68 | C++98 | no null characters were stored at the end of the output for overload (2) | stores a null character |
LWG 1203 | C++98 | overload for rvalue stream returned lvalue reference to the base class | returns rvalue reference to the derived class |
LWG 2328 | C++98 | overload for rvalue stream required another argument to be lvalue | made to accept rvalue |
LWG 2534 | C++98 | overload for rvalue stream was not constrained | constrained |