I am wondering what kind of things would cause fread() to return 0, for 0 items read from disk. After I have written to disk, and then try to read it in, with fread(), it returns 0, and I''m wondering why this is happening. Help is appreciated. Thanks.

This could happen because The FILE pointer is null.
If the FILE pointer is null, and you try to fread, it will return a 0. The FILE pointer could be null because the file doesn''t exist. When you want to read from a file, specify "r" in the fopen function.

Hope that helps.

Or maybe you''re trying to fread() from a text file? I don''t know if fread() works on text files, but it is possible that that''s what''s causing the trouble.

/. Muzzafarath
Mad House Software

I don''t think that''s it. I can use fread with a text file. No problem.But then again, that maybe be different from compiler to compiler?
I still think that you didn''t check the FILE pointer before using it. Anyway, post and tell us if our advice didn''t help you .

Well... I don''t think the FILE pointer is NULL, I could be wrong? Anyways, here is the code take a look. The load and save functions are here:


void Load(void)
{
strcpy(string2,loadedPlaybook);
strcpy(loadedPlaybook," ");

lpdd->FlipToGDISurface(); // dialog box gets name of playbook to load
DialogBox (hinst, TEXT ("PLAYBOOK_LOAD_DIALOG"), main_window_handle, &DlgProc);

if(strcmp(loadedPlaybook,"")){
// ensures the playbook goes in the default ''playbooks'' directory
sprintf(string1,"playbooks//%s.pbk",loadedPlaybook);
if(strcmp(loadedPlaybook," ")){
if(file_playbook = fopen(string1,"r")){ // opens the file specified by the user
fread(&playbook,sizeof(playbook),1,file_playbook);

fclose(file_playbook);
lpdd->FlipToGDISurface();
Message("Success","Playbook loaded successfully.");
EnableMenuItem(PLAYBOOK_menu,PLAYBOOK_SAVE,MF_ENABLED);
PLAYBOOK_LOADED = TRUE;

for(p=0;p<11;p++){
tempVar = p;
playbook.play[OFFENSIVE_PLAY_SELECTED].OPlayer[tempVar].sprite.x = LOS-playbook.play[OFFENSIVE_PLAY_SELECTED].OPlayer[tempVar].distanceFromLOS;
playbook.play[DEFENSIVE_PLAY_SELECTED].DPlayer[tempVar].sprite.x = LOS+playbook.play[DEFENSIVE_PLAY_SELECTED].DPlayer[tempVar].distanceFromLOS;
}
}
else{
Message("Error","Playbook doesn''t exist.");
strcpy(loadedPlaybook,string2);
}
} else strcpy(loadedPlaybook,string2);
}
else Message("Error","No playbook has been entered.");
}

void Save(void)
{
// makes loadedPlaybook = " "
strcpy(string2,loadedPlaybook);
strcpy(loadedPlaybook," ");

for(p=0;p<11;p++){ // for correct loading purposes
tempVar = p;
playbook.play[OFFENSIVE_PLAY_SELECTED].OPlayer[tempVar].distanceFromLOS = LOS - (int)playbook.play[OFFENSIVE_PLAY_SELECTED].OPlayer[tempVar].sprite.x;
playbook.play[DEFENSIVE_PLAY_SELECTED].DPlayer[tempVar].distanceFromLOS = (int)playbook.play[DEFENSIVE_PLAY_SELECTED].DPlayer[tempVar].sprite.x - LOS;
}

lpdd->FlipToGDISurface(); // dialog box gets name of playbook to save
DialogBox (hinst, TEXT ("PLAYBOOK_SAVE_DIALOG"), main_window_handle, &DlgProc);

if(strcmp(loadedPlaybook,"")){ // if loadedPlaybook is not blank
sprintf(string1,"playbooks//%s.pbk",loadedPlaybook);
if(file_playbook = fopen(string1,"r")){ // opens the file specified by the user
fclose(file_playbook); // ask if user wants to overwrite existing file
if(strcmp(loadedPlaybook," ")){
if(MessageBox(main_window_handle,"Playbook already exists, overwrite?","Playbook exists",MB_YESNO)==IDYES){
if(file_playbook = fopen(string1,"w")){ // create file
fwrite(&playbook,sizeof(playbook),1,file_playbook);
fclose(file_playbook);
Message("Playbook overwritten","Old playbook has been overwritten successfully with the new playbook.");
}
else Message("Error","Unable to save playbook.");
}
} else strcpy(loadedPlaybook,string2);
}
else{
if(file_playbook = fopen(string1,"w")){
if(strcmp(loadedPlaybook," ")){
fwrite(&playbook,sizeof(playbook),1,file_playbook);
fclose(file_playbook);
Message("Playbook saved","Playbook saved successfully.");
} else strcpy(loadedPlaybook,string2);
}
else Message("Error","Unable to save playbook.");
}
}
else Message("Error","No playbook has been entered.");
}

Sorry for the long, sloppy code... and how do you make the code smaller than your regular text? Thanks for your time.

>> how do you make the code smaller than your regular text? <<

Put all of your code between < code> < /code> tags (without the spaces). Or you could put it in [ source] [ /source] tags.

This is inside the code tag.


            This is inside the source tag. int void double    

/. Muzzafarath
Mad House Software

Edited by - Muzzafarath on June 11, 2000 11:24:10 AM

what is the "playbook" variable? a struct? maybe change this line to:


fread(&playbook,sizeof(PLAYBOOK_TYPE),filepointer);


(& then change the write the same way..)

this is so the sizeof() references the playbook''s type and not the variable itself..

just a possible problem I have had before. sometimes the compiler I have doesn''t like references to specific variables caus'' It can figure the size? (I assume)

http://www.ill-lusion.com

The weird thing about this is that it works sometimes. When I changed from sizeof(variable) to sizeof(variable_typ), it worked 2 times, and then didn''t work again! What is going on here?

that is not as strange as it sound (to me anyway...)

how do you create/destroy/handle the "playbook"?

you should probably "new" / "delete" it every time you load it. If it is not being freed/renewed properly this maybe your problem... don''t know what else to try without the rest of the source to examine...

Ziggy,

http://www.ill-lusion.com