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std::ios_base::fmtflags

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< cpp‎ | io‎ | ios base
Revision as of 01:53, 8 October 2013 by Eendy (Talk | contribs)

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typedef /*implementation defined*/ fmtflags;
static constexpr fmtflags dec = /*implementation defined*/

static constexpr fmtflags oct = /*implementation defined*/
static constexpr fmtflags hex = /*implementation defined*/

static constexpr fmtflags basefield = /*implementation defined (dec | oct | hex)*/
static constexpr fmtflags left = /*implementation defined*/

static constexpr fmtflags right = /*implementation defined*/
static constexpr fmtflags internal = /*implementation defined*/

static constexpr fmtflags adjustfield = /*implementation defined (left | right | internal)*/
static constexpr fmtflags scientific = /*implementation defined*/

static constexpr fmtflags fixed = /*implementation defined*/

static constexpr fmtflags floatfield = /*implementation defined (scientific | fixed)*/
static constexpr fmtflags boolalpha = /*implementation defined*/

static constexpr fmtflags showbase = /*implementation defined*/
static constexpr fmtflags showpoint = /*implementation defined*/
static constexpr fmtflags showpos = /*implementation defined*/
static constexpr fmtflags skipws = /*implementation defined*/
static constexpr fmtflags unitbuf = /*implementation defined*/

static constexpr fmtflags uppercase = /*implementation defined*/

Specifies available formatting flags. It is a BitmaskType, the following constants are defined:

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

[edit] Example

The following example shows several different ways to print the same result.

#include <iostream>
 
int main() 
{
    int num = 150;
 
    // using fmtflags as class member constants:
    std::cout.setf(std::ios_base::hex, std::ios_base::basefield);
    std::cout.setf(std::ios_base::showbase);
    std::cout << num << '\n';
 
    // using fmtflags as inherited class member constants:
    std::cout.setf (std::ios::hex , std::ios::basefield);
    std::cout.setf (std::ios::showbase);
    std::cout << num << '\n';
 
    // using fmtflags as object member constants:
    std::cout.setf(std::cout.hex, std::cout.basefield);
    std::cout.setf(std::cout.showbase);
    std::cout << num << '\n';
 
    // using fmtflags as a type:
    std::ios_base::fmtflags ff;
    ff = std::cout.flags();
    ff &= ~std::cout.basefield;   // unset basefield bits
    ff |= std::cout.hex;          // set hex
    ff |= std::cout.showbase;     // set showbase
    std::cout.flags(ff);
    std::cout << num << '\n';
 
    // not using fmtflags, but using manipulators:
    std::cout << std::hex << std::showbase << num << '\n';
}

Output:

0x96
0x96
0x96
0x96
0x96

[edit] See also

manages format flags
(public member function) [edit]
sets specific format flag
(public member function) [edit]
clears specific format flag
(public member function) [edit]
changes the base used for integer I/O
(function) [edit]
changes the fill character
(function template) [edit]
changes formatting used for floating-point I/O
(function) [edit]
controls whether prefix is used to indicate numeric base
(function) [edit]
switches between textual and numeric representation of booleans
(function) [edit]
controls whether the + sign used with non-negative numbers
(function) [edit]
controls whether decimal point is always included in floating-point representation
(function) [edit]
controls whether output is flushed after each operation
(function) [edit]
controls whether leading whitespace is skipped on input
(function) [edit]
controls whether uppercase characters are used with some output formats
(function) [edit]