Switch-case statement jumps to default instead of a case

For some reason the following code jumps from the first case to the default case :

Code:

    while(file.read(chunk,2))
    {
        switch(wordToshort(chunk))
        {
            case CHUNK_MAIN:

                cout<<"In main chunk "<< (int(file.tellg())-2) <<endl;
                success=true;
                file.read(length,4);
                break;
            case CHUNK_EDIT:

                cout<<"In edit chunk"<< (int(file.tellg())-2) <<endl;

                file.read(length,4);
                break;
            case CHUNK_TRIMESH_VERTS:

                cout<<"In object chunk"<<(int(file.tellg())-2) <<endl;
                file.read(length,4);
                break;
            default:
                cout<<"In default"<<endl;
                file.read(length,4);

                file.seekg(wordToshort(length),ios::beg);
                break;
        }
    }

This jumps from CHUNK_MAIN case to the default case ,although this code:

Code:

        switch(wordToshort(chunk))
        {
            case CHUNK_MAIN:

                cout<<"In main chunk "<< (int(file.tellg())-2) <<endl;
                success=true;
                file.read(length,4);
                break;
            case CHUNK_EDIT:

                cout<<"In edit chunk"<< (int(file.tellg())-2) <<endl;

                file.read(length,4);
                break;
            case CHUNK_TRIMESH_VERTS:

                cout<<"In object chunk"<<(int(file.tellg())-2) <<endl;
                file.read(length,4);
                break;
        }
    }

jumps from CHUNK_MAIN case to the CHUNK_EDIT case. Is this an error related to C++ syntax or is this possible something else?

cheers

You're saying it does this without going through another
while(file.read(chunk,2))
?

Yes ,that's the problem.

Did you put in a cout message after the while and before the switch to verify the while loop was not occurring twice? How do you know? Can you post a non-working complete example?

Originally Posted by Argyle

Yes ,that's the problem.

Unless you are using a comletely new compiler that no one else is using, I'm 99.99% sure that the problem is in your code, and not in the compiler. Switch statements are used quite often in code, so a compiler that isn't able to correctly compile switch statements would not get very far.

Perhaps "wordToShort" isn't returning what you exect, or some such? Add a temporary variable, assign it with wordToShort, and switch on the variable - then modify the code to print the variable before the switch.

--
Mats

Dino, if by non-working example, you mean what it outputs:
when the default case is commented it outputs:

In main chunk 0
In edit chunk

but when default case is uncommented it outputs:

In main chunk 0
In default

Now, AFAIK the existance of default case in the code shouldn't affect the values of 'chunk'.

Originally Posted by Argyle

Dino, if by non-working example, you mean what it outputs:
when the default case is commented it outputs:



but when default case is uncommented it outputs:



Now, AFAIK the existance of default case in the code shouldn't affect the values of 'chunk'.

What we're saying is: "it's a while loop, it's going to go through a bunch of different cases in a row." Are you not expecting wordToShort(chunk) to change, for some reason (such as, your file consists of the same two bytes over and over)?

My bad. I explained the problem badly . I don't mind the change in the 'chunk's value. It's just that the CHUNK_MAIN and CHUNK_EDIT cases should execute and not the CHUNK_MAIN and the default case. Things go well if there is no default case but as soon as the default case is added, it executes instead of the CHUNK_EDIT case.

Originally Posted by Argyle

My bad. I explained the problem badly . I don't mind the change in the 'chunk's value. It's just that the CHUNK_MAIN and CHUNK_EDIT cases should execute and not the CHUNK_MAIN and the default case. Things go well if there is no default case but as soon as the default case is added, it executes instead of the CHUNK_EDIT case.

What is the input and what do you get as output if you follow my suggestion?

I'm still 99.99% sure that the problem is in your code, not the compilers.

--
Mats

It seems the file I was reading was different kind from what I thought it was. I'm sorry I wasted your time.

Originally Posted by Argyle

It seems the file I was reading was different kind from what I thought it was. I'm sorry I wasted your time.

Yes, that's another alternative...

--
Mats

There you go - you've found a complete non-working example.