Clean code to printf size_t in C++ (or: Nearest equivalent of C99's %z in C++)

Question

I have some C++ code that prints a size_t:

size_t a;
printf(\"%lu\", a);

I\'d like this to compile without warnings on both 32

Answer 1

The effective type underlying size_t is implementation dependent. C Standard defines it as the type returned by the sizeof operator; aside from being unsigned and a sort of integral type, the size_t can be pretty much anything which size can accommodate the biggest value expected to be returned by sizeof().

Consequently the format string to be used for a size_t may vary depending on the server. It should always have the "u", but may be l or d or maybe something else...

A trick could be to cast it to the biggest integral type on the machine, ensuring no loss in the conversion, and then using the format string associated with this known type.