Creating several(400) data files within a program

I'm very new in c programming, so my quetion may seem fooly.

I write a program that calls gnuplot; it have to solve 200 ordinary diferential equiations. My question is: How I rename the images and the data files, so my program stores all the solutions and its graphics?

Thanks a lot.

you're going to need some practice, look up file streams...

the algorithm would work as such:
create a new file with preferred names,
copy data from one file to another,
delete old files.

http://www.cprogramming.com/tutorial/cfileio.html

no, it wouldn't.

http://www.cplusplus.com/reference/c...io/rename.html

oh... lol, oops... :-) well now i know.

i guess now that i think about it, what i said is extremely impractical...

But rename doesn't work. At last I don't see how.

My problem is this:

1. I solve an numerical integration and I save the data in a file, "file1.dat"
2. I call Gnuplot, and gnuplot uses "file1.dat" to create an image file, that I call "file1.eps"
3. I change the initial conditions of the equition and repeat the procces.

Now, If I use rename, it will be like this.

rename("file1.dat","file2.dat")

But what happen if I make another integration? ¿It isn't posible in C to do something like file[].dat, where [] is a variable which changes when a variable increses?

Instead of renaming the file, why not create it in a uniquely named file in the first place?

You could create a file-name using sprintf() for example...

--
Mats

I'm not sure I'm understanding you.

You say, put all the text in the same file? That's ok. And that work's fine without additional functions. But I still have the problem with the images files.

I've seen sprintf function, but I don't understand the idea very well.

If I say gnuplot to create an image file the first time, it's going to be whatever i say. The second time, sprintf will have create a file - if a do something like sprintf(string, "file. %d", file_number) -, but how I tell gnuplot to create the images in that file?

Sorry very much, but i have dificulties with english and with programming ideas, so i fell i don't get it the faster i have to.

Just stuff all of the data into one binary file. Why create 200 files?

Quote:

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but how I tell gnuplot to create the images in that file?

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Do you mean, how can you redirect gnuplot's output into a different file?

Ok. The first problem is solved (I save of the data in an unique file.dat).

The second problem is just what dwks say: ¿how can i save the gnuplot's output in different files ITERATIVELY? I need the 200 output images files!

I'm searching information about binary files (i'm new in c programming -in general in programming :) -)

Okay . . . so you want to generate a filename for gnuplot to save to, correct? Then you can either pass that directly to gnuplot for its output file, or rename gnuplot's output file to this new name.

Well, I think sprintf() would work well here, as you mentioned earlier.

Code:

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sprintf(filename, "file-%d.output", number);

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Then, when you execute gnuplot, use filename. If you're using system, consider something like (I don't know gnuplot's arguments):

Code:

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sprintf(command, "gnuplot %s -o %s", input, output);
system(command);

---

With exec*(), just pass output as another argument.

You'll have to be more specific. How are you calling gnuplot?

Perfect! I solved the problem! Actually I got more problems if a don't create the multiple data files, so I did this:

Code:

---

FILE    *fp[101]; //number of files I need
char    fname[25];

  for ( k = 0; k < 101; k++){
    sprintf(fname,"ros&#37;d.dat", k);
    fp[k] = fopen(fname, "w");
  }

---

And at the end I do...

Code:

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for ( i = 0; i < 101; i++) fp(fout[i]);

---

Thanks a lot for your sugestions.

About Gnuplot, I was calling it like this:

Code:

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#define GNUPLOT_PATH "/usr/local/bin"

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At the begining it worked, but then gnuplot don't show me something, or stored any graphics, so i made a little script which call the data files.