Re: Writing a .txt file

From:
Lucress Carol <incognito.me@gmx.de>
Newsgroups:
microsoft.public.vc.language
Date:
Tue, 1 Apr 2008 07:16:43 -0700 (PDT)
Message-ID:
<7c4b93b7-3e37-4a33-b3a4-99a12197e080@e23g2000prf.googlegroups.com>
On 1 Apr., 14:14, Ulrich Eckhardt <eckha...@satorlaser.com> wrote:

Lucress Carol wrote:

Does someone has an idea how I can write
the js and the number S in a .txt file?


Looking at your code, you already know how to output the values to stdout.=

What you can do is redirect stdout so that your program's output is writte=

n

to a file. For that, invoke your program like this:

  yourprogram.exe > output.txt

Alternatively, you can write to a file just as you write to std::cout:

  #include <fstream>

  std::ofstream out("output.txt");
  if(!out)
    throw std::runtime_error("failed to open file");
  out << "S=" << S << std::endl;

Note that both 'out' and 'std::cout' have a common baseclass 'std::ostream=

',

so you can write a function

  void write_array( std::ostream& out, double const* array, size_t size)=

;

which you could invoke with both an std::fstream and std::cout.

void RandomNum(double small,double big ,int p, double *array)
{
     double range=(big-small)+1;
    for (int i=0; i<p; i++){
   array[i]=small+int(range*rand()/(RAND_MAX + 1.0));
}
}


First thing here is that the formatting is messed up, probably due to a mi=

x

of tabs and spaces. Use only spaces for indention when posting on the
Usenet, and in general that's a good advise, too.

Second thing here is the fact that you are using C++ but passing arrays as=

pointer/size combo. You should have used a std::vector instead. Further, i=

t

isn't even done correctly, the size should use a size_t instead. You shoul=

d

also make a mental note that you can use std::generate to create sequences=

,

but that's for later when you know C++ much better.

Further, the way that you calculate the random number smells, I wouldn't
make any guarantees that this actually behaves mathematically correct.

srand((unsigned)time(0));


One thing here: please forget about the fact that this style of casts
exists. They are simply dangerous and not even needed in 99.9% of all C++
code. In this case, you should have used static_cast.

Uli

--
C++ FAQ:http://parashift.com/c++-faq-lite

Sator Laser GmbH
Gesch=E4ftsf=FChrer: Michael W=F6hrmann, Amtsgericht Hamburg HR B62 932


Thank you for the fast reply and the advices.

What you can do is redirect stdout so that your program's output is writte=

n

to a file. For that, invoke your program like this:

  yourprogram.exe > output.txt


Do you mean I have to invoke my program
over the console??

Second thing here is the fact that you are using C++ but passing arrays as=

pointer/size combo. You should have used a std::vector instead. Further, i=

t

isn't even done correctly, the size should use a size_t instead.


size_t?? never seen or heard of that before.How would have the array
looked like when using this size_t?could you give
an example.

srand((unsigned)time(0));


One thing here: please forget about the fact that this style of casts
exists.


Ok.I'm going to make a try with static_cast

Thank you

Lucress

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