C++ fopen fwrite with specific path i choose

Question

I'm writing a simple code on Linux that writes into a file. That file will be stored in specific path ( not the same path where the executable is located ).The problem is that when I execute the code , the program is terminating with segmentation fault (core dump)

Here is my code :

#include <stdio.h>

int main ()
{
  FILE * pFile;
  char buffer[] = { 'x' , 'y' , 'z' };
  pFile = fopen ("/home/medwajih/Desktop/bufferfile/buffer.txt", "wb");
  fwrite (buffer , sizeof(char), sizeof(buffer), pFile);
  fclose (pFile);
  return 0;
}

Note that the exe of the program is in "/home/medwajih/Desktop/" and the location where I want to create the buffer.txt file is "/home/medwajih/Desktop/bufferfile/"

Thank you.

Answer 1

If the fopen fails (such as if the /home/medwajih/Desktop/bufferfile directory does not exist, or the file exists but has permissions that disallow you replacing it), then pFile will be set to NULL.

Attempting to use it is then undefined behaviour.

You should generally check all calls that may fail to ensure they don't cause issues later on, such as with:

pFile = fopen ("/home/medwajih/Desktop/bufferfile/buffer.txt", "wb");
if (pFile == NULL) {
    fprintf (stderr, "Could not create file\n");
    return 1;
}

If the problem is actually that the directory does not exist, you can call mkdir beforehand. And, of course, check the return value of that as well :-)

If it's something else (there's not really enough information in the question to ascertain what it is), you need to find a different way to rectify the problem.