Saving top score in a file - c

Question

So I want to save the best 3 scores of the game and to put them on a file. But for some reason when I read the file the best scores are 53,32,32. Not using name for now, just the 3 scores. And also I'm not familiarized with files.
typedef struct score{
unsigned char score[3];
//char name[20];
} SCORES;
This is how I'm saving.
void guardar_highscore (SCORES top){
FILE *f;
f = fopen ("/var/www/html/highscore3.txt","wb");
if (f ==NULL)
perror ("nope2"),exit (1);
fprintf(f,"%d \n %d \n %d \n",top.score[0],top.score[1],top.score[2]);
fclose(f);
}
This is how I'm reading it to the struct.
SCORES ler_highscore (){
SCORES top={0};
int i=0;
char line[20];
FILE *f;
f = fopen ("/var/www/html/highscore3.txt","rb");
if (f ==NULL)
perror ("nope"), exit (1);
while(fgets(line,20, f) != NULL){
sscanf (line, "%c", &top.score[i]);
i++;
}
fclose(f);
return top;
}

Answer 1

typedef struct score{
unsigned char score[3];
//char name[20];
} SCORES;
Scores are generally numbers, so it doesn't make much sense to store them as a single character. The problem becomes clear when you notice that you're writing them as integers (and with an extra space)...
fprintf(f,"%d \n %d \n %d \n",top.score[0],top.score[1],top.score[2]);
But you're reading them as characters...
sscanf (line, "%c", &top.score[i]);
53, 32, 32 looks suspiciously like the ASCII numbers for 5 and two spaces. If you write the character 5 as a number you'll get 53. That's because the character 5 is the number 53. Have a look at the ASCII table to see why.
The solution is to use integers consistently.
typedef struct {
int score[3];
} Scores;
Note that ALL_CAPS is generally reserved for constants, not types.
guardar_highscore remains basically the same, though I've cleaned it up some.
// The filename is now a variable so its used consistently
// and can be used in error messages.
const char Score_File[] = "highscore3.txt";
void guardar_highscore(const Scores *top) {
FILE *fd = fopen (Score_File,"wb");
if (fd == NULL) {
// A more informative error message than "nope".
fprintf( stderr, "Could not open '%s' for writing: %s\n", Score_File, strerror(errno) );
exit(1);
}
// Loop instead of repeating the formatting. This makes adding more
// scores easier.
// Note the stray whitespace is gone.
for( int i = 0; i < 3; i++ ) {
fprintf(fd, "%d\n", top->score[i]);
}
fclose(fd);
}
ler_highscore() changes to read as integers. It also only reads three lines to protect against overflowing the 3 element list if the file is unexpectedly large. It's good practice to never trust your input.
Scores ler_highscore() {
// This is the proper way to initialize a struct,
// each field must be initialized separately.
// A bare {0} happens to work because the struct is
// currently just a list, and if it doesn't you're
// going to overwrite all the elements anyway.
Scores top = { .score = {0} };
// No reason to skimp on the size of the line buffer.
char line[1024];
FILE *fd = fopen(Score_File, "rb");
if (fd == NULL) {
// Again, more informative error message.
fprintf( stderr, "Could not open '%s' for reading: %s", Score_File, strerror(errno) );
exit (1);
}
// Read 3 lines, no more. Otherwise we'll overflow memory.
for( int i = 0; i < 3; i++ ) {
// Use `sizeof(line)` rather than repeating the number.
// It avoids mistakenly letting them go out of sync.
if( fgets(line, sizeof(line), fd) == NULL ) {
fprintf( stderr, "Not enough scores in %s\n", Score_File );
break;
}
// Read one integer per line.
sscanf(line, "%d", &top.score[i]);
}
fclose(fd);
return top;
}