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std::setiosflags

Defined in header <iomanip>
/*unspecified*/ setiosflags( std::ios_base::fmtflags mask );

When used in an expression out << setiosflags(mask) or in >> setiosflags(mask), sets all format flags of the stream out or in as specified by the mask.

Parameters

mask - bitmask of the flags to set

Return value

An object of unspecified type such that.

  • if out is an object of type std::basic_ostream<CharT, Traits>, the expression out << setiosflags(mask)
    • has type std::basic_ostream<CharT, Traits>&
    • has value out
    • behaves as if it called f(out, mask)
  • if in is an object of type std::basic_istream<CharT, Traits>, the expression in >> setiosflags(mask)
    • has type std::basic_istream<CharT, Traits>&
    • has value in
    • behaves as if it called f(in, mask)

where the function f is defined as:

void f(std::ios_base& str, std::ios_base::fmtflags mask)
{
    // set specified flags
    str.setf(mask);
}

Example

#include <iostream>
#include <iomanip>
 
int main()
{
    std::cout << std::resetiosflags(std::ios_base::dec) 
              << std::setiosflags(  std::ios_base::hex
                                  | std::ios_base::uppercase
                                  | std::ios_base::showbase) << 42 << '\n';
}

Output:

0X2A

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 183 C++98 setiosflags could only be used with streams
of type std::ostream or std::istream
usable with any
character stream

See also

sets specific format flag
(public member function of std::ios_base)
clears the specified ios_base flags
(function)

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https://en.cppreference.com/w/cpp/io/manip/setiosflags