Algorithmic performance in C: as a general rule, does recursion usually run slower than equivalent loops due to call overhead and stack usage?

Difficulty: Easy

Correct Answer: Yes

Explanation:


Introduction / Context:
Choosing between recursion and iteration affects performance and memory. While recursion can produce elegant code and is essential for certain problems (for example, divide-and-conquer), it typically incurs function-call overhead and consumes stack frames. This question asks about the usual, practical performance comparison in C.


Given Data / Assumptions:

  • Normal C implementations without mandatory tail-call optimization.
  • Equivalent algorithms can be expressed either recursively or iteratively.
  • Focus on typical workloads rather than contrived micro-benchmarks.


Concept / Approach:
Each recursive call generally pushes a new frame (return address, saved registers, locals) and performs a call/return sequence. Iterative loops avoid repeated call overhead by reusing a single frame. Unless a compiler applies tail-call elimination or inlining, the recursive version often runs slower and uses more stack.


Step-by-Step Solution:

Compare mechanics: recursion → multiple calls; loop → one frame.Estimate costs: call/return and stack traffic add overhead per level of recursion.Consider optimizations: tail-call optimization may reduce or eliminate overhead but is not guaranteed by ISO C.Conclude: in usual practice, recursion is slower than an equivalent well-written loop.


Verification / Alternative check:
Benchmark factorial or Fibonacci (memoized vs. iterative). Iterative versions typically outperform naive recursion in C.


Why Other Options Are Wrong:

No: ignores typical overhead.Only in interpreted languages: C is compiled; still, call overhead exists.Only on 8-bit MCUs: the observation holds broadly.Depends exclusively on optimization: optimization helps but does not universally make recursion faster.


Common Pitfalls:
Assuming tail-call optimization will always occur; forgetting stack limits and the risk of deep recursion.


Final Answer:
Yes.

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