Sets the numeric base of the stream. When used in an expressionout<< setbase(base) orin>> setbase(base), changes thebasefield flag of the streamout orin, depending on the value ofbase:

• the value16 setsbasefield tostd::ios_base::hex.
• the value8 setsstd::ios_base::oct.
• the value10 setsstd::ios_base::dec.

Values ofbase other than 8, 10, or 16 resetbasefield to zero, which corresponds to decimal output and prefix-dependent input.

[edit]Parameters

[edit]Return value

An object of unspecified type such that

• ifout is an object of typestd::basic_ostream<CharT, Traits>, the expressionout<< setbase(base)
  • has typestd::basic_ostream<CharT, Traits>&
  • has valueout
  • behaves as if it calledf(out, base)
• ifin is an object of typestd::basic_istream<CharT, Traits>, the expressionin>> setbase(base)
  • has typestd::basic_istream<CharT, Traits>&
  • has valuein
  • behaves as if it calledf(in, base)

where the functionf is defined as:

void f(std::ios_base& str,int base){// set basefield    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);}

[edit]Example

#include <iomanip>#include <iostream>#include <sstream> 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';}

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

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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