Because the logic of the circuit is only 0 and 1 two States, here 0 and 1 are not numbers 0 and 1, 0 and 1 are two different States, 0 means low level, 1 represents high level. Because the computer is composed of numerous logical circuits, information can be expressed only according to the infinite number and combination of 0 and 1.

And string uses the "\0" to be an ending while integer doesn't.