Question

We are interested in the implementation of a Unix/Linux system utility for the concatenation of a list of n text files. In order to do that we are going to consider the following syntax below where the concatenation of n text files are written in the output file all.txt or on the console if the output text file is not specified. In C

      $./mycat file_1.txt file_2.txt   . . .   file_n.txt > all.txt

Attach your solution, named mycat.c, here

Answer 1

Following code can be used.

int cbd_merge_files(const char** filenames, int n, const char* final_filename) {
  
  //opening files
  FILE* fp = fopen(final_filename, "wb");

  if (fp == NULL) return 1;

  char buffer[4097];
  //iterating over all the files to append
  for (int i = 0; i < n; ++i) {

    const char* fname = filenames[i];

    FILE* fp_read = fopen(fname, "rb");

    if (fp_read == NULL) return 1;

    int n;
   // appending the files.
    while ((n = fread(buffer, sizeof(char), 4096, fp_read))) {

        int k = fwrite(buffer, sizeof(char), n, fp);

        if (!k) return 1;
    }
    fclose(fp_read);

 }

 fclose(fp);

 return 0;
}

int main(int argc, const char** argv)
{
  cbd_merge_files(argv+1, argc-1, "output.txt");
  return 0;
}