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These methods control (or report on) settings for some details of
controlling streams, primarily to do with formatting output:
- Method: char ios::fill () const
-
Report on the padding character in use.
- Method: char ios::fill (char padding)
-
Set the padding character. You can also use the manipulator
setfill
. See section Changing stream properties using manipulators.
Default: blank.
- Method: int ios::precision () const
-
Report the number of significant digits currently in use for output of
floating point numbers.
Default: 6
.
- Method: int ios::precision (int signif)
-
Set the number of significant digits (for input and output numeric
conversions) to signif.
You can also use the manipulator setprecision
for this purpose.
See section Changing stream properties using manipulators.
- Method: int ios::width () const
-
Report the current output field width setting (the number of
characters to write on the next `<<' output operation).
Default: 0
, which means to use as many characters as necessary.
- Method: int ios::width (int num)
-
Set the input field width setting to num. Return the
previous value for this stream.
This value resets to zero (the default) every time you use `<<'; it is
essentially an additional implicit argument to that operator. You can
also use the manipulator setw
for this purpose.
See section Changing stream properties using manipulators.
- Method: fmtflags ios::flags () const
-
Return the current value of the complete collection of flags controlling
the format state. These are the flags and their meanings when set:
ios::dec
-
ios::oct
-
ios::hex
-
What numeric base to use in converting integers from internal to display
representation, or vice versa: decimal, octal, or hexadecimal,
respectively. (You can change the base using the manipulator
setbase
, or any of the manipulators dec
, oct
, or
hex
; see section Changing stream properties using manipulators.)
On input, if none of these flags is set, read numeric constants
according to the prefix: decimal if no prefix (or a `.' suffix),
octal if a `0' prefix is present, hexadecimal if a `0x' prefix
is present.
Default: dec
.
ios::fixed
-
Avoid scientific notation, and always show a fixed number of digits after
the decimal point, according to the output precision in effect.
Use
ios::precision
to set precision.
ios::left
-
ios::right
-
ios::internal
-
Where output is to appear in a fixed-width field; left-justified,
right-justified, or with padding in the middle (e.g. between a numeric
sign and the associated value), respectively.
ios::scientific
-
Use scientific (exponential) notation to display numbers.
ios::showbase
-
Display the conventional prefix as a visual indicator of the conversion
base: no prefix for decimal, `0' for octal, `0x' for hexadecimal.
ios::showpoint
-
Display a decimal point and trailing zeros after it to fill out numeric
fields, even when redundant.
ios::showpos
-
Display a positive sign on display of positive numbers.
ios::skipws
-
Skip white space. (On by default).
ios::stdio
-
Flush the C
stdio
streams stdout
and stderr
after
each output operation (for programs that mix C and C++ output conventions).
ios::unitbuf
-
Flush after each output operation.
ios::uppercase
-
Use upper-case characters for the non-numeral elements in numeric
displays; for instance, `0X7A' rather than `0x7a', or
`3.14E+09' rather than `3.14e+09'.
- Method: fmtflags ios::flags (fmtflags value)
-
Set value as the complete collection of flags controlling the
format state. The flag values are described under `ios::flags ()'.
Use ios::setf
or ios::unsetf
to change one property at a
time.
- Method: fmtflags ios::setf (fmtflags flag)
-
Set one particular flag (of those described for `ios::flags ()';
return the complete collection of flags previously in effect.
(Use
ios::unsetf
to cancel.)
- Method: fmtflags ios::setf (fmtflags flag, fmtflags mask)
-
Clear the flag values indicated by mask, then set any of them that
are also in flag. (Flag values are described for `ios::flags
()'.) Return the complete collection of flags previously in
effect. (See
ios::unsetf
for another way of clearing flags.)
- Method: fmtflags ios::unsetf (fmtflags flag)
-
Make certain flag (a combination of flag values described for
`ios::flags ()') is not set for this stream; converse of
ios::setf
. Returns the old values of those flags.
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