Question

I know this is wrong but I have no clue where to go from here. The difficulty is from 0-2. I have files for the game board labeled "10.txt" to "39.txt". This function needs to randomize which of the 10 boards is chosen then returns the open file address.

FILE* open_game_file(int difficulty) {

   game_choice(difficulty);
   difficulty += 1;
   difficulty *= 10;
   int i;
   i = rand() % 10;
       i += difficulty;
       infile = fopen("", "r");
   return 0;
}

Answer 1

I'm assuming you used C for this. Here is the complete code for operating the function. Explanation's in the comments above each line.

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

FILE* open_game_file(int difficulty){
//game_choice(difficulty); //some function ???
difficulty+=1;
difficulty*=10;
//seed it with time
srand (time(NULL));
int i=rand()%10;
i+=difficulty;
FILE *infile;

//create a string pointer with some dummy data, but right format
char fname[7]="xy.txt";
//replace the 0th index of the fname char array with tens place digit of i
fname[0]=(i/10)+48;
//replace the 0th index of the fname char array with ones place digit of i
fname[1]=(i%10)+48;
//+48 to convert into ASCII characters for digits (48-57)
//check the value of fname out by printing, to see if it's OK
printf("%s opened",fname);
//initialize the file pointer with fname. (Mode has been set to w to show you it can write to any valid file)
infile=fopen(fname,"w");
//return that file pointer
return infile;
}

int main(){
//declare and initialize a file pointer with the function
FILE *game=open_game_file(2);
//Just show that you can write to a valid file pointed to by our pointer. You can do whatever you want regarding to the file now that you have the pointer.
fprintf(game,"Hello Gameboard");
//properly close it
fclose(game);
}

Output in terminal:

36.txt opened

In 36.txt

Hello Gameboard