std::ios_base::setf

C++

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ios_base::ios_base

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Formatting

ios_base::flags

ios_base::setf

ios_base::unsetf

ios_base::precision

ios_base::width

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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. 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. 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 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)