Manipulating files through C to make a top 5 leaderboard - c

Question

I'm making a connect 4 game as apart of a project and I want to add extra functionality to it, however I'm struggling.
The code is a function I've written that takes a struct (lb leaderboard) and attempts to read the file for that difficulty of all its inputs into a lb array size of 6 which include the difficulty of the bot, turn count and the name of the player, then organizes it in order of turn count and reprints the top 5 back into the file.
I set the first element of the old array to the passed by struct of leaderboard data for the organise function bit.
However, when i set it up with template inputs each separated with a new line like such:
0 7 James
0 13 Jimmy
0 8 Joshua
0 6 Charly
0 9 Jack
It prints this to the file:
0 7 James
0 13 Jimmy
0 8 Joshua
0 6 Charly
(0 9 Jack 1982289408 0 ) same line
The struct looks like this as well{
int turn_count
int diff
char name[20]}
I'm really new to coding so any help is appreciated!
lb old[6];
lb temp;
FILE *file;
if (leaderboard.diff == 0){
file = fopen("leaderboard0.txt", "r+");}
else if (leaderboard.diff == 1){
file = fopen("leaderboard1.txt", "r+");}
else if (leaderboard.diff == 2){
file = fopen("leaderboard2.txt", "r+");}
fseek( file, 1, SEEK_SET );
old[0] = leaderboard;
for (int i = 1; i < 6; i++){
fscanf(file, "%i %i %s", old[i].diff, old[i].turn_count, old[i].name);}
for (int i = 0; i < 6; i++){
for (int j = i + 1; j < 6; j++)
if (old[i].turn_count > old[j].turn_count)
{
temp = old[i];
old[i] = old[j];
old[j] = temp;
}}
for (int i = 0; i < 5; i++){
fprintf(file, "%i %i %s\n", old[i].diff, old[i].turn_count, old[i].name);
fclose(file);}
}

Answer 1

Welcome to StackOverflow, JJewson
First of all, I strongly recommend to you to properly indent your code. One error will be obvious only by that:
lb leaderboard = { ... }; /* was missing from your source code */
lb old[6]; /* you should rename this */
lb temp;
FILE *file;
/* somthing that opens a block was missing from your example source */ {
if (leaderboard.diff == 0) {
file = fopen("leaderboard0.txt", "r+");
} else if (leaderboard.diff == 1) {
file = fopen("leaderboard1.txt", "r+");
} else if (leaderboard.diff == 2) {
file = fopen("leaderboard2.txt", "r+");
}
fseek( file, 1, SEEK_SET );
old[0] = leaderboard;
for (int i = 1; i < 6; i++) {
fscanf(file, "%i %i %s", old[i].diff, old[i].turn_count, old[i].name);
}
for (int i = 0; i < 6; i++) {
for (int j = i + 1; j < 6; j++) {
if (old[i].turn_count > old[j].turn_count) {
temp = old[i];
old[i] = old[j];
old[j] = temp;
}
}
}
for (int i = 0; i < 5; i++) {
fprintf(file, "%i %i %s\n", old[i].diff, old[i].turn_count, old[i].name);
fclose(file); /* this is the obvious error, it should go below this loop */
}
fclose(file); /* here it should be */
}
It would be probably best to rename leaderboard to leader and after that to rename old to leaderboard.
I already mentioned the need to move the fclose call outside of the loop. You close the file after your first write.
I don't understand your first use of fseek( file, 1, SEEK_SET );: Why do you skip the first character of the file? (File offsets start at 0 not 1). Also: After a successfull fopen, the file pointer always points to the beginning of the file.
After you read your leaderboard, you should fclose the file, and reopen it for (over-)writing. (Better keep a backup, if the leader board is important). So: Open "r" for reading, read, close, open "w" for writing, write, close.
You don't do any error checking in your code. You should fix that and inform the user on error and try to handle the error as gracefully as possible. (I.e. do not loose your leaderboard if writing fails.)
Concerning the added part 1982289408 0: Make sure, your new leader (struct `leaderboard´) is properly initialized).
Your algorithm has a slight problem: A new player, who was exactly as good as a previous one, will move that previous one out of the leader board. To fix that, load the file into old[0..4] and put new leader into old[5] (instead of putting him in old[0] and the file content in old[1..5])
Minor imporovement: The sorting loop: for (int i = 0; i < 6; i++) for (int j = i + 1; j < 6; j++)-> thefor iloop only needs to run from 0 .. 4, sofor (int i = 0; i < 5; i++)` would suffice.