size_t == sizeof (uint64_t) not returning expected results [closed]

I'm compiling a C++ DLL from a reasonably well-vetted library (zeromq), and consuming it in my own Delphi bindings. I'm currently hitting an unexpected behavior in the C++ code, and don't have the background to debug it well. The ultimate responsibility for the bug is probably in my Delphi code, but I need to understand the C++ better to know what I did wrong.

The problem code looks like this (simplified)

 if (*mySize_tObject == sizeof (uint64_t)) {     return 0;//We never reach this code. }

*mySize_tObject is passed in as a size_t. In my Delphi bindings, it is a Cardinal with a value of 8.

I've tried playing around with the C++ outputs to narrow down what might be happening, and gotten these results:

return *mySize_tObject;//8return sizeof (uint64_t);//8return *mySize_tObject + sizeof (uint64_t);//16

if (*mySize_tObject  == sizeof(uint64_t)) {    return 1;}else if (*mySize_tObject  < sizeof(uint64_t)) {    return 2; }else if (*mySize_tObject  > sizeof(uint64_t)) {    return 3;//This is the value that returns}else {    return 0;}

So I'm getting back, essentially, 8>8. Since I know that isn't true (citation needed), I'm left thinking that one of these values is secretly a float like 8.000001 and I'm only seeing truncated results.

I would also consider tips for live debugging a .dll if this doesn't make any sense to people that know C++.

I guess it's also worth noting that I previously had my Delphi bindings working in 32bit, and started running into these difficulties while converting to 64bit (I also changed the DLL compiling settings to match).

I apologize for not being able to produce a minimal reproducible example, but I'll try to give as much detail about my calls as I can here:

The Delphi binding:

TMyBinding = function(var mySize_tObject : size_t): Integer; cdecl;

The value being passed is instantiated as SizeOf( result ), with result being an Int64.

*Note: size_t is defined elsewhere as a Cardinal in the Delphi code.

The header for this function in C++:

int myFunct(size_t *mySize_tObject ) const;