Question

I want to run another program from my C++ code. system() returns int, as every program can only return int to the os. However, the other program I want to call will generate a string that I need in my base app. How can I send it to the parent process?

The two apps will be in the same folder, so I think that the child app can save the string to “temp.txt” and then the main app may read and delete it (it’s not performance critical process, I will call another process just to call open file dialog in my main opengl app). However this is a bit ugly solution, are there better cross platform solutions?

Thanks

Answer 1

You could use popen(), this opens a process where you can write and read data. AFIK this is also cross plattform

// crt_popen.c
/* This program uses _popen and _pclose to receive a 
 * stream of text from a system process.
 */
#include <stdio.h>
#include <stdlib.h>

int main(void) {

   char   psBuffer[128];
   FILE   *pPipe;

        /* Run DIR so that it writes its output to a pipe. Open this
         * pipe with read text attribute so that we can read it 
         * like a text file. 
         */

   if((pPipe = _popen("dir *.c /on /p", "rt")) == NULL)
      exit(1);

        /* Read pipe until end of file. */

   while(!feof(pPipe)) {
      if(fgets(psBuffer, 128, pPipe) != NULL)
         printf(psBuffer);
   }

        /* Close pipe and print return value of pPipe. */

   printf("\nProcess returned %d\n", _pclose(pPipe));

   return 0;
}