C / C++ / MFC

8-Mar-03 7:25

Maybe...

Try handling all the messages in the tab class like this:

HWND dialog = GetParent(this);
PostMessage(dialog, themessage);

you can get themessage since it is specific to the handler in ur tabcontrol.
I wouldnt know though it's just a guess. Big Grin | :-D

Kuniva
--------------------------------------------

fclose() error

Kuniva8-Mar-03 6:00

8-Mar-03 6:00

Hi, i am writing a function to read in certain data from a file using stdio.h
but when i try to close the file handle with fclose() windows gives me the error "Myapp.exe has encountered a problem and needs to close. blablabla..."

This is the code:

FILE *npf;
char id[3];
float version;


if((npf = fopen(FileName, "rb")) == NULL)  // FileName is a global char with a valid file name
{
    fclose(npf);
    return FALSE;
}
if(fseek(npf, 0L, SEEK_SET))
{
    fclose(npf);
    return FALSE;
}

fscanf(npf, "%s", id);
//fscanf(npf, "%f", &version);

//char vers[10];
//sprintf(vers, "%f", version);


string IDs;
IDs.append(id);
//ID.append(" ");
//ID.append(vers);

MessageBox (NULL, IDs.c_str() , "ID", 0 + MB_ICONASTERISK);

fclose(npf); // <---- this is where i get my error from windows
return TRUE;

Also, you can see the lines i commented out where i try to read a float after reading the string, when i leave those in, i get the error at the line fscanf(npf, "%f", &version)
Can anyone tell me whats causing this? I looked at an example from the MSDN about file streams and i've worked with them before so i don't really see whats wrong here.

Thanks

P.S.: Yes, the file is big enough for the string and the float to be read.

Kuniva
--------------------------------------------

C^hris L^osinger8-Mar-03 6:43

C^hris L^osinger

8-Mar-03 6:43

is the string longer than 2 characters? if so, you're overrunning the "id" buffer.

also, try opening the file in "r" mode, , not "rb".

-c

When history comes, it always takes you by surprise.

Bobber!

Kuniva8-Mar-03 7:16

8-Mar-03 7:16

the string is 3 characters("npf"), but i thought it was like this:
id[0]="n"
id[1]="p"
id[2]="f"

and since it is id[3] there should be enough room.. right?

so dont u mean longer than 3 characters?

and i also thought the fscanf function reads in the data dependant of the size of the variable that is passed, so that it cant overrun the buffer...
or is this incorrect? i'm just guessing though, it's what i'd presume since there arent any other parameters passed to fscanf() which indicate what length it is.

But anyways, that cant be the problem anyways because i can display the id fine in a messagebox, the error only shows when i use fclose() or maybe after that... i'm not sure, because this is code for a function in a class i am writing. This is what i do(the class is called CNPFfile):

int main(int argc, char *argv[])
{
    CNPFfile npf("npffile.npf");
    BOOL bv = npf.IsValidNpfFile();
    return 1;
}

I also tried opening the file in "r" mode, that didnt help.

Thank you kindly

Kuniva
--------------------------------------------

C^hris L^osinger8-Mar-03 8:28

C^hris L^osinger

8-Mar-03 8:28

a string will have a 0 byte at the end. to read a 3 character string, you need a four byte buffer.

-c

When history comes, it always takes you by surprise.

Bobber!

Kuniva8-Mar-03 7:42

8-Mar-03 7:42

OO WAIT lol
if i make it id[1000] then it works without errors... hmm so i guess fscanf doesnt get the number of bytes to read from the variable passed, oops. Hmm strange..

But anyways, what i'm actually trying to do here is to read in a serialised file, but not entirely, just some sort of header with a constant length. Like for example these are the first 8 bytes and the matching ASCII thingies:
6E 70 66 00 05 00 00 00
n p f

so i would think fscanf would stop at the 00 no?? Geesh this is complicated, maybe there is another function i should use for this? (i don't want to use MFC) I tried fread() already but didnt know how to start reading from a certain position with that cause i thought it always just started at the beginning, or can i use fseek() for that as well??

Kuniva
--------------------------------------------

Tim Smith8-Mar-03 16:13

Tim Smith

8-Mar-03 16:13

I have been using C for nearly 20 years now. scanf is still a total mystery to me. Laugh | :laugh:

Since you are just passing the address of the string to fscanf, it has no idea how much space it can write over. This is one of many problems iostreams tried to fix with print/scanf.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Kuniva8-Mar-03 8:11

8-Mar-03 8:11

ok nevermind, it appears i can use fread for the job, thanks anyways

Kuniva
--------------------------------------------

Abbas_Riazi8-Mar-03 18:04

Abbas_Riazi

8-Mar-03 18:04

Did you add null character end of id?
change your code to this:

<br />
char id[4]=NULL;<br />
fscanf(npf, "%s", id);<br />
id[3]='\0';<br />
//other code goes here<br />

A. Riazi

ModifyStyle dynamically

Gumball8-Mar-03 5:37

Gumball

8-Mar-03 5:37

Hello All,

I have been having a problem I just don't know how to get by. I have a common dialog set up that I configure as I need at run-time. The default properties in the rc is CHILD and no FRAME (which is the majority of the times I need it) I have tried to change it to a pop-up window using ModifyStyle as well as SetWindowLong with out any luck. Anyone have any suggestions as to how this can be accomplished?

School Project in C

Claus Jobes8-Mar-03 4:58

Claus Jobes

8-Mar-03 4:58

I'm not sure if someone in here can help. For a school project my son needs to write a code module in C to find the multiplicative inverse of ( X mod(26) ) using C-code if X and 26 HAVE common prime factors.

I'm a VB person and can't help him at all. Anybody out there that could give some advice?

Thanks

Claus

dog_spawn8-Mar-03 6:58

dog_spawn

8-Mar-03 6:58

Is the problem with the math or the code? If you post a vb function that does it, then it will be simple to port it to C.

Claus Jobes8-Mar-03 7:05

Claus Jobes

8-Mar-03 7:05

I guess I wasn't clear enough. I have no clue how to go about this and was hoping for a code example that would help me to understand how to do this.

Claus

yaname8-Mar-03 12:38

yaname

8-Mar-03 12:38

If Y is a multiplicative inverse of X mod(26) then (X*Y) mod(26) = 1. But the only factors of 26 are the primes 2 and 13, so if X and 26 have common prime factors then X = 26*Z. Then (X*Y) mod(26) = (Z*Y*26) mod(26) = 0 for any Y, so X has no multiplicative inverse mod 26.

This looks like it might be helpful.

http://math.uh.edu/~minru/web/lincong2.html