VBA Data Types and Limits LongPtr


Dim Value As LongPtr

The LongPtr was introduced into VBA in order to support 64 bit platforms. On a 32 bit system, it is treated as a Long and on 64 bit systems it is treated as a LongLong.

It's primary use is in providing a portable way to store and pass pointers on both architectures (See Changing code behavior at compile time.

Although it is treated by the operating system as a memory address when used in API calls, it should be noted that VBA treats it like signed type (and therefore subject to unsigned to signed overflow). For this reason, any pointer arithmetic performed using LongPtrs should not use > or < comparisons. This "quirk" also makes it possible that adding simple offsets pointing to valid addresses in memory can cause overflow errors, so caution should be taken when working with pointers in VBA.

The casting function to convert to a LongPtr is CLngPtr(). For casts from floating point types, the result is rounded to the nearest integer value with .5 rounding up (although since it is usually a memory address, using it as an assignment target for a floating point calculation is dangerous at best).