Structured programming principle: Which construct is forbidden by the principles of structured programming?

Introduction / Context:
Structured programming advocates building programs from a small set of well-defined control structures to improve readability, maintainability, and correctness. Understanding which constructs fit this paradigm is essential.

Given Data / Assumptions:

• Structured constructs include sequence, selection, and iteration.
• GOTO introduces arbitrary jumps that can create “spaghetti code”.
• We assume standard imperative languages as context.

Concept / Approach:

Structured programming replaces unrestrained jumps with structured loops and conditionals. WHILE–DO, DO–WHILE, and IF–THEN–ELSE fit within these constructs. GOTO undermines structure by enabling non-local, unstructured control flow.

Step-by-Step Solution:

Verification / Alternative check:

Programming methodology literature encourages eliminating GOTO in favor of structured alternatives, allowing easier reasoning and formal verification.

Why Other Options Are Wrong:

• WHILE–DO, DO–WHILE: Structured loops; encouraged.
• IF–THEN–ELSE: Core selection construct; encouraged.
• None of the above: Incorrect because GOTO is indeed discouraged/forbidden by the principle.

Common Pitfalls:

Believing GOTO is never used; in rare low-level scenarios or generated code it appears, but structured design avoids it in source-level logic.

Final Answer:

GOTO