write_file.c

#include<stdlib.h>
#include<stdio.h>

main() {
  FILE *f = fopen("file.txt", "w");
  if (f == NULL)
  {
    printf("Error opening file!\n");
    exit(1);
  }

  const char *text = "This data will be written to disk";
  fprintf(f, "%s\n", text);
  fclose(f);
}