C++ Stream manipulators
Introduction
Manipulators are special helper functions that help controlling input and output streams using operator >> or operator <<.
They all can be included by #include <iomanip>.
Remarks
Manipulators can be used in other way. For example:
os.width(n);equals toos << std::setw(n);
is.width(n);equals tois >> std::setw(n);
os.precision(n);equals toos << std::setprecision(n);
is.precision(n);equals tois >> std::setprecision(n);
os.setfill(c);equals toos << std::setfill(c);
str >> std::setbase(base);orstr << std::setbase(base);equals to
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);
os.setf(std::ios_base::flag);equals toos << std::flag;
is.setf(std::ios_base::flag);equals tois >> std::flag;
os.unsetf(std::ios_base::flag);equals toos << std::no ## flag;
is.unsetf(std::ios_base::flag);equals tois >> std::no ## flag;
(where ## - is concatenation operator)
for nextflags:boolalpha,showbase,showpoint,showpos,skipws,uppercase.
std::ios_base::basefield.
Forflags:dec,hexandoct:
os.setf(std::ios_base::flag, std::ios_base::basefield);equals toos << std::flag;
is.setf(std::ios_base::flag, std::ios_base::basefield);equals tois >> std::flag;
( 1 )str.unsetf(std::ios_base::flag, std::ios_base::basefield);equals tostr.setf(std::ios_base::fmtflags(0), std::ios_base::basefield);
( 2 )
std::ios_base::adjustfield.
Forflags:left,rightandinternal:
os.setf(std::ios_base::flag, std::ios_base::adjustfield);equals toos << std::flag;
is.setf(std::ios_base::flag, std::ios_base::adjustfield);equals tois >> std::flag;
( 1 )str.unsetf(std::ios_base::flag, std::ios_base::adjustfield);equals tostr.setf(std::ios_base::fmtflags(0), std::ios_base::adjustfield);
( 2 )
( 1 ) If flag of corresponding field previously set have already unset by unsetf.
( 2 ) If flag is set.
std::ios_base::floatfield.
os.setf(std::ios_base::flag, std::ios_base::floatfield);equals toos << std::flag;
is.setf(std::ios_base::flag, std::ios_base::floatfield);equals tois >> std::flag;
forflags:fixedandscientific.os.setf(std::ios_base::fmtflags(0), std::ios_base::floatfield);equals toos << std::defaultfloat;
is.setf(std::ios_base::fmtflags(0), std::ios_base::floatfield);equals tois >> std::defaultfloat;
str.setf(std::ios_base::fmtflags(0), std::ios_base::flag);equals tostr.unsetf(std::ios_base::flag)
forflags:basefield,adjustfield,floatfield.
os.setf(mask)equals toos << setiosflags(mask);
is.setf(mask)equals tois >> setiosflags(mask);
os.unsetf(mask)equals toos << resetiosflags(mask);
is.unsetf(mask)equals tois >> resetiosflags(mask);
For almost allmaskofstd::ios_base::fmtflagstype.
