What about the types int2, int3, float2, float3 etc

Question

I\'ve seen different code snippets using these types, but I haven\'t seen if they are defined in some or just defined in a \"local header file\"

Answer 1

These types are not standard and I've never seen them. Are you sure they weren't used as (terrible choices of) identifiers instead of types?

Some non-standard types that are quite likely available anyway are int32_t, uint64_t, etc. (These are specified by C99, so most modern C++ compilers also let you use them in C++.)