The flags(), setf(), and unsetf() methods set or retrieve a set of format flags maintained within the istream or ostream object.
The I/O Stream Format Flags
| Flag | Description |
|---|---|
| boolalpha | Displays bool as either true or false rather than 1 or 0. |
| dec | Reads or writes integers in decimal format (default). |
| fixed | Displays floating point in fixed point as opposed to scientific (default). |
| hex | Reads or writes integers in hexadecimal. |
| left | Displays output left justified (i.e., pads on the right). |
| oct | Reads or writes integers in octal. |
| right | Displays output right justified (i.e., pads on the left). |
| scientific | Displays floating point in scientific format. |
| showbase | Displays a leading 0 for octal output and leading 0x for hexadecimal output. |
| showpoint | Displays a decimal point for floating-point output even if the fractional portion is 0. |
| skipws | Skips over whitespace when reading using the extractor. |
| unitbuf | Flushes output after each output operation. |
| uppercase | Replaces lowercase letters with their uppercase equivalents on output. |
The following code shows how to display numbers in hexadecimal format:
// read the current format flags ios_base::fmtflags prevValue = cout.flags(); // clear the decimal flag cout.unsetf(cout.dec); /*from ww w. j av a 2 s . co m*/ // now set the hexadecimal flag cout.setf(cout.hex); // call flags() to restore the format flags to their previous value cout.flags(prevValue);