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

Defined in header <bitset>

Defined in header `<bitset>`
template< class CharT, class Traits, std::size_t N > std::basic_ostream<CharT, Traits>& operator<<( std::basic_ostream<CharT, Traits>& os, const std::bitset<N>& x );	(1)
template< class CharT, class Traits, std::size_t N > std::basic_istream<CharT, Traits>& operator>>( std::basic_istream<CharT, Traits>& is, std::bitset<N>& x );	(2)

template< class CharT, class Traits, std::size_t N >
std::basic_ostream<CharT, Traits>&
    operator<<( std::basic_ostream<CharT, Traits>& os, const std::bitset<N>& x );

(1)

template< class CharT, class Traits, std::size_t N >
std::basic_istream<CharT, Traits>&
    operator>>( std::basic_istream<CharT, Traits>& is, std::bitset<N>& x );

(2)

Inserts or extracts a bitset from a character stream.

1) Writes the bitset x to the character stream os as if by first converting it to a std::basic_string<CharT,Traits> using to_string(), and then writing it into os using the operator<< (which is a FormattedOutputFunction for strings).
The characters to use for ones and zeroes are obtained from the currently-imbued locale by calling std::use_facet<std::ctype<CharT>>(os.getloc()).widen() with '1' and '0' as arguments.

2) Behaves as a FormattedInputFunction. After constructing and checking the sentry object, which may skip leading whitespace, extracts up to N characters from is and stores the characters in the bitset x.
Characters are extracted until either

N characters have been read,
end-of-file occurs in is, or
the next character is neither is.widen('0') nor is.widen('1').

If N > 0 and no characters are extracted, is.setstate(ios_base::failbit) is called.

Parameters

os	-	the character stream to write to
is	-	the character stream to read from
x	-	the bitset to be read or written

Return value

1) os

2) is

Example

#include <bitset>
#include <iostream>
#include <sstream>

int main()
{
    std::string bit_string = "001101";
    std::istringstream bit_stream(bit_string);
    
    std::bitset<3> b1;
    bit_stream >> b1; // reads "001", stream still holds "101"
    std::cout << b1 << '\n';
    
    std::bitset<8> b2;
    bit_stream >> b2; // reads "101", populates the 8-bit set as "00000101"
    std::cout << b2 << '\n';
}

Output:

001
00000101

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 303	C++98	single-byte characters were extracted from `is`, but `CharT` can have multiple bytes	extracts `CharT` and compares it with widened `'0'` and `'1'`
LWG 396	C++98	the content written by operator<< was locale-independent	writes widened `'0'`s and `'1'`s
LWG 3199	C++98	extracting a `std::bitset<0>` always sets `failbit`	such extraction never sets `failbit`

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

Parameters

Return value

Example

Defect reports

See also