2009 May 03 - Sun

64 Bit Data Models

As we move to 64 bit processors, variable types and their widths change. I had originally thought that there would be a consistent naming convention as one moved from 32 bit programming to 64 bit programming. At a 64 Bit Wiki Entry, I find that such is not the case. Different compilers choose different ways. For example the Microsoft VC compiler will use the LLP64 model which keeps an int as 32 bits. This is something that one needs to keep in mind when re-compiling software created for 32 bit processors in a 64 bit environment.

In the same article, mention is made that it is a good habit to make use of 'ptrdiff_t', which is declared in , when subtracting two pointers and using the result.