> Code Used:

> (std::cout).width(10);
> std::cout << std::showpos << 123456.78;

> Output:
>    +123457
> instead of +123456.78

> Please tell me as to why this is happening?

>> Code Used:

>> (std::cout).width(10);
>> std::cout << std::showpos << 123456.78;

>> Output:
>>    +123457
>> instead of +123456.78

>> Please tell me as to why this is happening?

>The problem is not width, it's precision. Width is 10 all
right - note
>three spaces in front of the number. But you've never
changed precision,
>and it's 6 significant digits by default. Try this:

>cout << setw(10) << setprecision(8) << showpos <<
123456.78

>or this

>cout << setw(10) << fixed << setprecision(2) << showpos
<< 123456.78

>The differece is that the first prints in general format
(assuming the
>format was not changed earlier), where precision is the
number of
>significant digits. The second prints in fixed format
where precision
>gives the number of digits after the decimal point.
>--
>With best wishes,
>    Igor Tandetnik

>"For every complex problem, there is a solution that is
simple, neat,
>and wrong." H.L. Mencken

>.

>Wrong. ostream::operator<<() for floating point numbers
defers to
>num_put locale facet. C++ standard 22.2.2.2.2 defines
num_put::do_put in
>terms of printf and specifies how a printf conversion
specifier is
>determined by ios_base flags. Fixed format becomes %f,
scientific
>becomes %e, and general format (the default) becomes %g.
Precision is
>added to the specifier. ios_base::showpos is represented
by + modifier.
>So, in your case with showpos and precision, say, 6, the
format becomes
>%+.6g in general format and %+.6f in fixed format.

>Now, C++ standard does not define the behavior of printf,
but instead
>defers to C standard. C99 7.19.6.1/4 says:

>An optional precision that gives ... the number of digits
to appear
>after the decimal-point character for a, A, e, E, f, and
F conversions,
>the maximum number of significant digits for the g and G
conversions ...

>Note how the meaning of precision field differs between %
f and %g.
>--
>With best wishes,
>    Igor Tandetnik

>"For every complex problem, there is a solution that is
simple, neat,
>and wrong." H.L. Mencken

>.