Final answer:
Undefined results in right or left bitwise shifts occur in signed integer operations when the sign bit is altered or in unsigned integers when a left shift causes a bitwise overflow. It is crucial to understand the language-specific behavior to use bitwise shifts correctly.
Step-by-step explanation:
When discussing R or L shifts, we assume this refers to right and left bitwise shifts respectively in programming and computer science. An undefined result can occur during right (R) or left (L) bitwise shifts if the operation is performed on a signed integer where the value being shifted into the sign bit (the most significant bit for a signed value) can change the sign of the result. In many programming languages, such as C and C++, this behavior is not defined by the standard when shifting into the sign bit of a signed integer. For unsigned integers, the left shift operation can result in undefined behavior if the operation causes a bitwise overflow, meaning that the bits shifted out are not equal to zero. Right shift on an unsigned integer is typically well-defined, filling with zeros from the left.
It is always important to understand the behavior of the programming language being used and ensure that the shifts are used appropriately to prevent undefined results. Special care should be taken when shifting negative numbers or when shifting by a number greater or equal to the number of bits in the operand's type.