Is it possible to declare two variables of different types in a for loop?

No – but technically there is a work-around (not that i’d actually use it unless forced to):

for(struct { int a; char b; } s = { 0, 'a' } ; s.a < 5 ; ++s.a) 
{
    std::cout << s.a << " " << s.b << std::endl;
}