Which data type to use for a very large numbers in C++?

Question

I have to store the number 600851475143 in my program. I tried to store it in long long int variable and long double as well but on compil

Answer 1

You had the right idea with long long int (or unsigned long long int), but to prevent the warning, you need to tell the compiler that the constant is a long long int:

long long int value = 600851475143LL;

Those "L"s can be lower-case, but I'd advise against it -- depending on the font, a lower-case "L" often looks a lot like a one digit ("1") instead.