How to redirect the output of a system call to inside the program in C/C++?

Question

I'm writing a program in C++ which do some special treatment for all the files in the current directory on Linux OS.

So i was thinking of using system calls such as system("ls") to get the list of all files.

but how to store it then inside my program ? ( how to redirect the output of ls to let's say a string that i declared in the program )

Thanks

Answer 1

I suggest you don't call out to ls - do the job properly, using opendir/readdir/closedir to directly read the directory.

Code example, print directory entries:

// $ gcc *.c && ./a.out 
#include <stdlib.h> // NULL
#include <stdio.h>  
#include <dirent.h>

int main(int argc, char* argv[]) {
  const char* path = argc <= 1 ? "." : argv[1];

  DIR* d = opendir(path);
  if (d == NULL) return EXIT_FAILURE;

  for(struct dirent *de = NULL; (de = readdir(d)) != NULL; )
    printf("%s/%s\n", path, de->d_name);

  closedir(d);
  return 0;
}