Question

I’m trying to compile and run the app, which was created 4 years ago. It was developed for Windows in Embarcadero RAD Studio C++ builder. Now I try to compile and run it in Windows in VirtualBox using the latest version of RAD Studio. I have a system call to another app in my app:

      system("dot.exe -Tjpg -o nfa.jpg NFA_graph.txt");

It keeps returning 1 and the file is not created. I also tried

      system("Echo %CD% >> z:\log.txt");

and the file is not created. I also tried like this:

FILE *fpipe;
char *command = "Echo %CD% >> z:\log.txt";
char line[256];

if (0 == (fpipe = (FILE*)_popen(command, "r")))
{
    perror("popen() failed.");
    exit(1);
}

while (fread(line, sizeof line, 1, fpipe))
{
    ShowMessage(line);
}

_pclose(fpipe);

And nothing I get. I wonder if the reason of such strange behaviour is that I’m running this all in VirtualBox?

Answer 1

You’re not escaping your \ characters. You should use / in file paths, or \\ if you must. In addition, Windows 7 won’t let you write to the root directory of a hard drive w/o administrator access.

To determine if a command environment is available, first do this:

if (!system(NULL)) {
    // Can't make any system() calls
}

If your command environment is available, then you need to fully specify the path, making sure to escape the \’s like I mentioned above, and don’t write anything to a drive’s root directory. Also make note that opening files does not default create directories.