std::dec, std::hex, std::oct

Defined in header <ios>
std::ios_base& dec( std::ios_base& str );
std::ios_base& hex( std::ios_base& str );
std::ios_base& oct( std::ios_base& str );

Modifies the default numeric base for integer I/O.

1) sets the basefield of the stream str to dec as if by calling str.setf(std::ios_base::dec, std::ios_base::basefield).

2) sets the basefield of the stream str to hex as if by calling str.setf(std::ios_base::hex, std::ios_base::basefield).

3) sets the basefield of the stream str to oct as if by calling str.setf(std::ios_base::oct, std::ios_base::basefield).

This is an I/O manipulator. It may be called with an expression such as out << std::hex for any out of type std::basic_ostream or with an expression such as in >> std::hex for any in of type std::basic_istream.


str - reference to I/O stream

Return value

str (reference to the stream after manipulation).


#include <iostream>
#include <sstream>
int main()
    std::cout << "The number 42 in octal:   " << std::oct << 42 << '\n'
              << "The number 42 in decimal: " << std::dec << 42 << '\n'
              << "The number 42 in hex:     " << std::hex << 42 << '\n';
    int n;
    std::istringstream("2A") >> std::hex >> n;
    std::cout << std::dec << "Parsing \"2A\" as hex gives " << n << '\n';


The number 42 in octal:   52
The number 42 in decimal: 42
The number 42 in hex:     2a
Parsing "2A" as hex gives 42

See also

changes the base used for integer I/O
controls whether prefix is used to indicate numeric base

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