From: Jason Green <news AT jgreen4 DOT fsnet DOT co DOT uk>
To: Eric Nute <nute AT iprg DOT nokia DOT com>
Cc: djgpp AT delorie DOT com
Subject: Re: Problems with strings while using djgpp
Date: Wed, 18 Oct 2000 23:40:54 +0100
Message-ID: <lj9sus088vebmr17ejephg3qbt0ttpnipg@4ax.com>
References: <39EB742E DOT 28DBB7BB AT iprg DOT nokia DOT com> <v0bpusc72mlpao90a7j3cjajp2mhv8hrrc AT 4ax DOT com> <39ECEB0D DOT E1D1E601 AT iprg DOT nokia DOT com>
In-Reply-To: <39ECEB0D.E1D1E601@iprg.nokia.com>
X-Mailer: Forte Agent 1.7/32.534
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by delorie.com id SAA20742
Reply-To: djgpp AT delorie DOT com

Your last message would have bounced, so I'll quote it in full here.

On Tue, 17 Oct 2000 17:13:01 -0700, you wrote:

> #include <iostream>
> #include <iomanip>
> #include <string>
> using namespace std;
> 
> int main(void)
> {  string car = "Yugo";
>    double tank = 6.36, mpg = 36;
> 
>    cout << setiosflags(ios::fixed);
>    cout << "Car         Tank   MPG    Range" << endl;
> 
>    cout << setiosflags(ios::left) << setw(12) << car  //setw() may not
> work
>         << setiosflags(ios::right) << setw(7) << setprecision(1) << tank
>         << setw(7) << mpg
>         << setw(7) << setprecision(0) << tank * mpg << endl;
> 
>    car = "Rolls Royce\0";
>    tank = 35;
>    mpg = 11.2;
> 
>    cout << setiosflags(ios::left) << setw(12) << &car[0]   //setw() fix
>         << setiosflags(ios::right) << setw(7) << setprecision(1) << tank
>         << setw(7) << mpg
>         << setw(7) << setprecision(0) << tank * mpg << endl;
> 
> 
>    return 0;
> }
> 
> 
> Output:
> 
> Car         Tank   MPG    Range
> Yugo    6.4   36.0    229
> Rolls Royceion d+   35.0   11.2    392
> 
> 
> Analysis:  setw() does not actually set the width of the string car =
> "Yugo".  The only space between Yugo and the next value is because of
> setw(7) before the value of tank.
> 
> The remedy, namely use C style pointers to refer to the string, does not
> work because the string class does not seem to input a \0 character at
> the end of the inputed string.  
> 
> I would appreciate any feedback as to how I can make the names and
> results line up.

Your original complaint that setw() does not work with C++ strings
appears to be valid.  

Since C strings appear to work ok, a suitable workaround would indeed
be to convert the C++ string to a C string as you suggest.  

Unfortunately, the method you use to do this won't work.  In fact, it
is completely implementation dependent as to what it will do, but I
think we can safely say it doesn't work with gcc (and there is no
reason why it should).

The correct method is to use c_str(), like this:

   cout << setiosflags(ios::left) << setw(12) << car.c_str()

Note that setiosflags(ios::left) is itself a workaround because the
'left' manipulator is missing; you should be able to do:

   cout << left << setw(12) << car

I posted a fix for this a while back.  Search the mail archives for
"left" and "iomanip" if you are interested.