gang gang skrt skrt

void replace (char *, char *, char *);

int main(int argc, char *argv[]){
  FILE *f = fopen("Input.txt", "r");
  FILE *output =fopen("Dante.txt", "w");
  char str[500];

//alerts user if file doesn't exist
  if (f == NULL){
    printf("File not exist.\n");
    exit(0);
  }

//Changing the words to the new words in the file
  while(fgets(str, 500, f)){
    for(int i = 0; i < 500; i++){
	if(strstr(str, "Inferno") != NULL){
            replace(str, "Inferno", "Paradiso");
        }
	if(strstr(str, "In dark woods") != NULL){
            replace(str, "In dark woods", "using Windows 8.1");
        }
        if(strstr(str, "those woods") != NULL){
            replace(str, "those woods", "Windows 8.1");
        }
        if(strstr(str, "to enter") != NULL){
            replace(str, "to enter", "to use 8.1");
        }
        if(strstr(str, "crest") != NULL){
            replace(str, "crest", "screen");
        }
        if(strstr(str, "Below a hill") != NULL){
            replace(str, "Below a hill", "Before a monitor");
        }
        if(strstr(str, "shoulders") != NULL){
            replace(str, "shoulders", "GUI");
        }
        if(strstr(str, "planet") != NULL){
            replace(str, "planet", "Shakespeare");
        }
    }
    fprintf(output,"%s", str);
  }

  fclose(f);
  return 0;
}


void replace(char * o_string, char * s_string, char * r_string) {

      //a variable to replace things
      char buffer[1000];

      //to store the pointer returned from str
      char * ch;

      //exit condition
      if(!(ch = strstr(o_string, s_string)))
              return;

      //copy all the content to buffer before the first occurrence of the search string
      strncpy(buffer, o_string, ch-o_string);

      //prepare the buffer for appending by adding a null to the end of it
      buffer[ch-o_string] = 0;

      //append using sprintf function
      sprintf(buffer+(ch - o_string), "%s%s", r_string, ch + strlen(s_string));

      //empty o_string for copying
      o_string[0] = 0;
      strcpy(o_string, buffer);

      //pass recursively to replace other occurrences
      return replace(o_string, s_string, r_string);
 }