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Storing a 64-bit Value

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To store a 64-bit pointer value, use ULONG_PTR. A ULONG_PTR value is 32 bits when compiled with a 32-bit compiler and 64 bits when compiled with a 64-bit compiler.

The following examples use real-world code that has been ported to 64-bit Windows. Commentary on the steps to make the code 64-bit compatible is included.

Example 1: Getting an Address

The following code illustrates a portable way to get an address.

Method Result
Using ULONG (a 32-bit-only method) 
ULONG getAnAddress( )Int *somePointerReturn( (ULONG) somePointer );
Using ULONG_PTR (the portable method) 
ULONG_PTR getAnAddress( )Int *somePointerReturn( (ULONG_PTR) somePointer );

 

Example 2: Calculating an Address

The following code illustrates a portable way to calculate an address.

Method Result
Using ULONG (a 32-bit-only method) 
Int *somePointer;Int *someOtherPointer;somePointer = (int *)( (ULONG)someOtherPointer + 0x20 );
Using ULONG_PTR (the portable method) 
Int *somePointer;Int *someOtherPointer;somePointer = (int *)( (ULONG_PTR)someOtherPointer + 0x20 );