Why are types always a certain size no matter its value?

Question

Implementations might differ between the actual sizes of types, but on most, types like unsigned int and float are always 4 bytes. But why does a type always occupy a certai

Answer 1

There are pretty substantial runtime performance benefits from doing this. If you were to operate on variable size types, you would have to decode each number before doing the operation (machine code instructions are typically fixed width), do the operation, then find a space in memory big enough to hold the result. Those are very difficult operations. It's much easier to simply store all of the data slightly inefficiently.

This is not always how it is done. Consider Google's Protobuf protocol. Protobufs are designed to transmit data very efficiently. Decreasing the number of bytes transmitted is worth the cost of additional instructions when operating on the data. Accordingly, protobufs use an encoding which encodes integers in 1, 2, 3, 4, or 5 bytes, and smaller integers take fewer bytes. Once the message is received, however, it is unpacked into a more traditional fixed-size integer format which is easier to operate on. It's only during network transmission that they use such a space-efficient variable length integer.