Longptr is a memsize type: it is a 32-bit size integer in 32-bit compilation and a 64-bit size integer in 64-bit compilation. This way, it can always hold a pointer value without being truncated and without needing to use a compiler switch.
Use Longptr for integer values that may hold a pointer value.
The single-character identifier for this type is “P”, while Integer is “I”. This makes the following a statement to set a constant to a value of type Longptr:
Define SOME_LARGE_VALUE for |CP$03762874671
For more information, refer to Declaring Variables and the Longptr command.