# std::ios_base::setf

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< cpp‎ | io‎ | ios base

fmtflags setf( fmtflags flags ); | (1) |
fmtflags setf( fmtflags flags, fmtflags mask ); | (2) |

Sets the formatting flags to specified settings.

1) Sets the formatting flags identified by `flags`. Effectively the following operation is performed fl = fl | flags where `fl` defines the state of internal formatting flags.
2) Clears the formatting flags under `mask`, and sets the cleared flags to those specified by `flags`. Effectively the following operation is performed fl = (fl & ~mask) | (flags & mask) where `fl` defines the state of internal formatting flags.

### Parameters

flags, mask

-

new formatting setting. `mask` defines which flags can be altered, `flags` defines which flags of those to be altered should be set (others will be cleared). Both parameters can be a combination of the following constants:

Constant | Explanation
`dec` | use decimal base for integer I/O: see std::dec
`oct` | use octal base for integer I/O: see std::oct
`hex` | use hexadecimal base for integer I/O: see std::hex
`basefield` | dec|oct|hex|0. Useful for masking operations
`left` | left adjustment (adds fill characters to the right): see std::left
`right` | right adjustment (adds fill characters to the left): see std::right
`internal` | internal adjustment (adds fill characters to the internal designated point): see std::internal
`adjustfield` | left|right|internal. Useful for masking operations
`scientific` | generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific
`fixed` | generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed
`floatfield` | scientific|fixed|(scientific|fixed)|0. Useful for masking operations
`boolalpha` | insert and extract bool type in alphanumeric format: see std::boolalpha
`showbase` | generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase
`showpoint` | generate a decimal-point character unconditionally for floating-point number output: see std::showpoint
`showpos` | generate a + character for non-negative numeric output: see std::showpos
`skipws` | skip leading whitespace before certain input operations: see std::skipws
`unitbuf` | flush the output after each output operation: see std::unitbuf
`uppercase` | replace certain lowercase letters with their uppercase equivalents in certain output output operations: see std::uppercase

### Return value

the formatting flags before the call to the function

### Example

Run this code

    #include <iostream>
    #include <iomanip>

    const double PI = 3.1415926535;

    int main()
    {
        const int WIDTH = 15;

        std::cout.setf(std::ios::right);  //equivalent: cout << right;
        std::cout << std::setw(WIDTH/2) << "radius"
                  << std::setw(WIDTH) << "circumference" << '\n';

        std::cout.setf(std::ios::fixed);
        for (double radius = 1; radius <= 6; radius += 0.5) {
            std::cout << std::setprecision(1) << std::setw(WIDTH/2)
                      << radius
                      << std::setprecision(2) << std::setw(WIDTH)
                      << (2 * PI * radius) << '\n';
        }
    }

Output:

    radius  circumference
        1.0           6.28
        1.5           9.42
        2.0          12.57
        2.5          15.71
        3.0          18.85
        3.5          21.99
        4.0          25.13
        4.5          28.27
        5.0          31.42
        5.5          34.56
        6.0          37.70

### See also

flags | manages format flags (public member function)
unsetf | clears specific format flag (public member function)

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