#include <stdio.h>

void copy_file(const char *source_filename, const char *destination_filename) {
  FILE *source_file, *destination_file;
  char buffer[1024];
  size_t bytes_read, bytes_written;

  // Open the source file for reading.
  source_file = fopen(source_filename, "r");
  if (source_file == NULL) {
    printf("Error opening source file: %s\n", source_filename);
    return;
  }

  // Open the destination file for writing.
  destination_file = fopen(destination_filename, "w");
  if (destination_file == NULL) {
    printf("Error opening destination file: %s\n", destination_filename);
    fclose(source_file);
    return;
  }

  // Read a block of data from the source file into the buffer.
  bytes_read = fread(buffer, 1, sizeof(buffer), source_file);
  while (bytes_read > 0) {
    // Write the block of data from the buffer to the destination file.
    bytes_written = fwrite(buffer, 1, bytes_read, destination_file);
    if (bytes_written != bytes_read) {
      printf("Error writing to destination file: %s\n", destination_filename);
      fclose(source_file);
      fclose(destination_file);
      return;
    }

    // Read another block of data from the source file into the buffer.
    bytes_read = fread(buffer, 1, sizeof(buffer), source_file);
  }

  // Close the source file.
  fclose(source_file);

  // Close the destination file.
  fclose(destination_file);
}

int main() {
  copy_file("source.txt", "destination.txt");

  return 0;
}

gcc -o copy copy.c
./copy