Typical errors of porting C++ code on the 64-bit platform

In all books devoted to the development of the quality code it is recommended to set a warning level of warnings shown by the compiler on as high level as possible. But there are situations in practice when for some project parts there is a lower diagnosis level set or it is even set off. Usually it is very old code which is supported but not modified. Programmers who work over the project are used to that this code works and don’t take its quality into consideration. Here it is a danger to miss serious warnings by the compiler while porting programs on the new 64-bit system.

While porting an application you should obligatory set on warnings for the whole project which help to check the compatibility of the code and analyze them thoroughly. It can help to save a lot of time while debugging the project on the new architecture.

If we won’t do this the simplest and stupidest errors will occur in all their variety. Here it is a simple example of overflow which occurs in a 64-bit program if we ignore warnings at all.

unsigned char *array[50];
unsigned char size = sizeof(array);
32-bit system: sizeof(array) = 200
64-bit system: sizeof(array) = 400