How to plot data by c program?

Question

I am a mechanical engineer who has only limited knowledge in C programming. I wrote some code in order to make simulations, and I want to visualize the simulation results. At the moment I am using Dev-C for writing my codes. With fopen and fprintf commands I generate a .dat file which includes the results. Then I open GNUPLOT program and import my .dat file to plot the results. This takes time and I have to wait till the end of the simulation. Is there an easy way to connect my plotter with Dev-C, so my plotter starts plotting data during the simulation? Any library or etc. ?

Answer 1

Since you already know gnuplot, the simplest thing to do may be to just call gnuplot from your program and pipe the data to it:

FILE *gnuplot = popen("gnuplot", "w"); fprintf(gnuplot, "plot '-'\n"); for (i = 0; i < count; i++)     fprintf(gnuplot, "%g %g\n", x[i], y[i]); fprintf(gnuplot, "e\n"); fflush(gnuplot); 

Answer 2

OK, one solution, as you are writing out to a file, would be to just make a system() call when you write out to the file, and call gnuplot.

But, that means you should change the filename each time, but I fear if you do that that it won't look correct, since you are sending small amounts of data each time.

http://www.gnu.org/software/libc/manual/html_node/System-Calls.html

I have never used gnuplot, but if you look at this page (http://gnuplot-tricks.blogspot.com/) you may find some tricks that would enable this to work well.

But, I think, unless you are going to plot everything yourself, and skip gnuplot, then you may just need to wait, as you are.

You may find the C interface to gnuplot may help you:

http://ndevilla.free.fr/gnuplot/