std::ios_base::setf
From cppreference.com
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
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
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 formatting flags |
Formatting flags
| 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 <iomanip> #include <iostream> #include <numbers> int main() { const double PI = std::numbers::pi; 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); // equivalent: cout << 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
| manages format flags (public member function) |
|
| clears specific format flag (public member function) |