What are arithmetic underflow and overflow in C?

Question

What do arithmetic underflow and overflow mean in C programming?

Answer 1

Computers use only 0 and 1 to represent data so that the range of values that can be represented is limited. Many computers use 32 bits to store integers, so the largest unsigned integer that can be stored in this case is 2^32 -1 = 4294967295. But the first bit is used to represent the sign, so, in fact, the largest value is 2^31 - 1 = 2147483647.

The situation where an integer outside the allowed range requires more bits than can be stored is called an overflow.

Similarly, with real numbers, an exponent that is too small to be stored causes an underflow.