# std::setiosflags

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< cpp‎ | io‎ | manip

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

Run this code

    #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

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

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