system()

[devarishi]

The function system() can be used for executing a DOS Command or Application from inside an executing program.

Exaple:

#include <stdio.h>
#include <stdlib.h>

void main() {

  printf("Listing the Directory Contents:\n");
  
  system("dir");

  printf("\nPress any key to exit from the program...");  
  getch();

  exit(0);

}

The above example program does display the output of the printf() function but the code line:

system("dir");

doesn't work.


Any help?

[c++0x]

#include <stdio.h>
#include <stdlib.h>

void main() {
  FILE *dir = popen("dir", "r");
  char line[500];

  printf("Listing the Directory Contents:\n");

  while(fgets(line, sizeof line, dir))
    puts(line);

  pclose(dir);

  printf("\nPress any key to exit from the program...");  
  getch();

  return 0;
}

Happy?

[devarishi]

Hi,


Thanks for your post but it's not what I wanted to do. I want to display the contents of a folder containg files and folders by running the DIR command of DOS.

However, your program's modified version is here as the original one would not run:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

void main() {

  FILE *dir = fopen("dir.txt", "r");
  char line[500];

  printf("Listing the Directory Contents:\n");

  while(fgets(line, sizeof line, dir))
    puts(line);

  fclose(dir);

  printf("\nPress any key to exit from the program...");
  getch();

}

The above program reads and displays the contents of a named file which is here in our example is "dir.txt".

#include <stdio.h>
#include <stdlib.h>

void main() {
  FILE *dir = popen("dir", "r");
  char line[500];

  printf("Listing the Directory Contents:\n");

  while(fgets(line, sizeof line, dir))
    puts(line);

  pclose(dir);

  printf("\nPress any key to exit from the program...");  
  getch();

  return 0;
}

Happy?

[c++0x]

But you don't want to open a file, you want to open a process. What was popen doing?

[foxman]

I don't know which environnement (C runtime) you are using, but look for the documentation on the system function call. Then, check the return value of the system call. Because I don't see why your "system("dir")" call would fail on a normal Windows system.

[c++0x]

Or POSIX. Nor do I c y my popen code not work.

[c++0x]

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int main(void)
{
  FILE *dir = popen("dir", "r");
  char line[500];

  assert(dir != NULL);

  printf("Listing the Directory Contents:\n");

  while(fgets(line, sizeof line, dir))
  {
    puts(line);
    fflush(stdout);
  }

  pclose(dir);

  printf("\nPress any key to exit from the program...");  
  getch();

  return 0;
}

Mayb? I don no y my popen not workd. Mayb cuz I cpy ur void main() lol. I fix it tho.

[c++0x]

Wait! If dir not work with system. I bet u dat ur PATH variable is buggred up. Fix ur PATH environment variable. If dats da case, popen won't work eithr. It will just crash n burn.

[brewbuck]

The problem is that "dir" is not the name of any program. It is an internal command delegate of cmd.exe. You need:

system("cmd /c dir");

EDIT: if you don't understand what's going on here, you shouldn't be doing this.

[Salem]

> Wait! If dir not work with system. I bet u dat ur PATH variable is buggred up. Fix ur PATH environment variable. If dats da case, popen won't work eithr. It will just crash n burn.
http://www.catb.org/~esr/faqs/smart-...html#writewell

I mean your first post was quite sane, but now your speech is just an open sewer.

[jwenting]

The function system() can be used for executing a DOS Command or Application from inside an executing program.

On Solaris too?

[devarishi]

Hi,


"Nonportable pointer conversion" warning message is being flagged highlighting the code line:

FILE *dir = popen("dir", "r");

Just now I have tried it again and this time included dos.h and process.h header files also. But the same error message is coming there.

I corrected the function main() also.

But you don't want to open a file, you want to open a process. What was popen doing?

[matsp]

You probably don't have popen() - try _popen() if you are using visual studio or gcc-mingw.

--
Mats

[devarishi]

Well, it is also not working. The same error message, as given above, is there.

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int main(void)
{
  FILE *dir = popen("dir", "r");
  char line[500];

  assert(dir != NULL);

  printf("Listing the Directory Contents:\n");

  while(fgets(line, sizeof line, dir))
  {
    puts(line);
    fflush(stdout);
  }

  pclose(dir);

  printf("\nPress any key to exit from the program...");  
  getch();

  return 0;
}

Mayb? I don no y my popen not workd. Mayb cuz I cpy ur void main() lol. I fix it tho.

[devarishi]

The given below code doesn't display anything on the console/screen.

system("cmd /c dir");

Well, my Path is also correct. I am using TC & TCPP (Turbo C++ ) compilers. However, now I have installed VC++ 2005 Express Edition also.

The problem is that "dir" is not the name of any program. It is an internal command delegate of cmd.exe. You need:

system("cmd /c dir");

EDIT: if you don't understand what's going on here, you shouldn't be doing this.