Problems with 64 bit pointers

Question

I am using Windows 7 and have a 64 bit and a 32 bit version of my program. The 32 bit version works perfectly fine, however, I am having issues with the 64 bit version at runtime. I have a list view item created and am filling the columns with my information. All of them are printing, but one is not printing correctly. This is what it is printing (I apologize for the lack of a picture but as a new member I am unable to post pictures):

Truck

ÍÍÍÍHRZ141

ÍÍÍÍHRZ152

It seems to be placing 4 null characters before the information I actually want it to display. Upon further examination, it appears as though the addressing is incorrect. Here is a section of my code where the error is occurring:

Audit * audit = (Audit *)plvdi->item.lParam;

    switch(plvdi->item.iSubItem)
    {
    case 0:
      {
        plvdi->item.pszText = audit->Truck;
        while(plvdi->item.pszText[0] != 'H')
        {
          plvdi->item.pszText++;
        }
      }
      return true;

This is a temporary fix due to the fact that all of my truck names start with the character H. plvdi->item.psz text is the text display of the list view item, and audit->Truck is a char[]. It should be as simple as:

sprintf(plvdi->item.pszText, audit->Truck);

but that doesn't seem to work. It leaves me with the same error. When run, the address plvdi->item.pszText is 4 bytes less than the address of audit->Truck, after the assignment statement (breakpoint on the while statement), which I believe is causing the 4 null characters. I am just unsure as to how to resolve this problem without a work around such as the one I posted, why this is happening, and why only in the 64 bit solution. Thank you in advance for any help on this matter.

EDIT: From other similar problems I have found within my program, it seems to have something to do with pointers. Everything in my Audit class that came after a selections vector was having problems and appeared to be off by 4 bytes. In another class, I found that everything coming after a pointer to an Audit failed and I also had some issues with strings (which are technically pointers to char arrays). When I moved the elements with pointers to the end of the class in the header file, everything seemed to work fine again. Any idea if strings, vectors, or other similar structures have pointers that are dependent upon 32 or 64 bit systems?

Answer 1

On 64 bit windows platform, sizeof of a pointer is 8 bytes, while is 4 on a 32 bit configuration. Check your code to avoid the 4 bytes size assumption.