In C/C++ control flow, what is the role of the break statement inside a switch selection statement, and is its use mandatory or optional for each case?

Introduction / Context:
Control flow in C and C++ often uses switch statements to select one of many branches based on an integral or enumeration value. Understanding how the break statement works inside switch is a fundamental competency, because it determines whether control 'falls through' to subsequent case labels or exits the switch block immediately.

Given Data / Assumptions:

• The context is a C or C++ switch statement with one or more case labels and an optional default label.
• The behavior of break is the standard language behavior; no compiler extensions are assumed.
• We focus on correctness and readability of typical application code.

Concept / Approach:
Within a switch statement, execution starts at the first matching case label and then continues sequentially. The break statement terminates the switch, transferring control to the statement following the switch block. If break is omitted intentionally, execution falls through to the next case label, which can be useful for grouped behavior. Therefore, break is not mandatory; it is optional but commonly used to prevent unintended fall-through.

Step-by-Step Solution:
Identify the matched case label from the switch expression.If a break statement is encountered during that case's block, exit the switch immediately.If break is not present, control continues into the next case label (fall-through) until a break or the end of the switch is reached.Thus, using break is optional; its presence changes control transfer, not language validity.

Verification / Alternative check:
Compile and run a small example where one case omits break and observe that subsequent case code executes. Add break and verify that execution stops at the end of the case block, demonstrating the optional nature of break.

Why Other Options Are Wrong:

• Compulsory: False; the language allows fall-through when break is omitted.
• Not allowed / gives an error: Break is standard and valid inside switch.
• To check an error: Break does not perform error checking; it controls flow.
• None of the above: Incorrect because break is optional.

Common Pitfalls:
Unintentional fall-through causes logic bugs. Use explicit break or a comment/attribute indicating intentional fall-through to improve clarity.

Final Answer:
optional.