std::setbase (3) - Linux Manuals

std::setbase: std::setbase

NAME

std::setbase - std::setbase

Synopsis

Defined in header <iomanip>
/*unspecified*/ setbase( int base );

Sets the numeric base of the stream. When used in an expression out << setbase(base) or in >> setbase(base), changes the basefield flag of the stream out or in, depending on the value of base:

* the value 16 sets basefield to std::ios_base::hex
* the value 8 sets std::ios_base::oct
* the value 10 sets std::ios_base::dec.

Values of base other than 8, 10, or 16 reset basefield to zero, which corresponds to decimal output and prefix-dependent input.

Parameters

base - new value for basefield

Return value

Returns an object of unspecified type such that if str is the name of an output stream of type std::basic_ostream<CharT, Traits> or std::basic_istream<CharT, Traits>, then the expression str << setbase(base) or str >> setbase(base) behaves as if the following code was executed:

  str.setf(base == 8 ? std::ios_base::oct :
              base == 10 ? std::ios_base::dec :
                  base == 16 ? std::ios_base::hex :
                       std::ios_base::fmtflags(0),
           std::ios_base::basefield);

Example

// Run this code

  #include <iostream>
  #include <sstream>
  #include <iomanip>
  int main()
  {
      std::cout << "Parsing string \"10 0x10 010\"\n";

      int n1, n2, n3;
      std::istringstream s("10 0x10 010");
      s >> std::setbase(16) >> n1 >> n2 >> n3;
      std::cout << "hexadecimal parse: " << n1 << ' ' << n2 << ' ' << n3 << '\n';

      s.clear();
      s.seekg(0);
      s >> std::setbase(0) >> n1 >> n2 >> n3;
      std::cout << "prefix-dependent parse: " << n1 << ' ' << n2 << ' ' << n3 << '\n';

      std::cout << "hex output: " << std::setbase(16)
                << std::showbase << n1 << ' ' << n2 << ' ' << n3 << '\n';
  }

Output:

  Parsing string "10 0x10 010"
  hexadecimal parse: 16 16 16
  prefix-dependent parse: 10 16 8
  hex output: 0xa 0x10 0x8