miscon:programming.functions.base-case-not-needed · draft · trust low · v0.1.2 · kind misapplied-analogy

A recursive function stops by itself

A recursive function stops calling itself when there is nothing left to do, so it does not need an explicit base case.

Stable URI: https://open-misconceptions.github.io/miscon-data/m/programming.functions.base-case-not-needed
UUID: 09dac977-0121-45e8-8a5c-0aa059faf59c
Domain: programming.functions
Level band: middle, secondary, undergraduate
Locale: en
About: https://open-misconceptions.github.io/miscon-data/c/programming.functions.base-case (Miscon)

Evidence patterns

Pattern 0: predict the behaviour of a recursive function with no base case

predicts termination with a sensible answer

Item

def count_down(n):
    print(n)
    count_down(n - 1)
count_down(3)

Expected3 2 1 0 -1 ... until the recursion limit is hit

Response3 2 1

Pattern 1: write a recursive function

omits the base case

ItemWrite factorial(n) recursively.

Expected

if n == 0: return 1
return n * factorial(n - 1)

Responsereturn n * factorial(n - 1)

Discriminators

vs a slip. A slip is one forgotten base case the learner adds when asked how it stops. The belief is the answer 'it stops when n runs out'.

vs programming.functions.recursion-as-loop. Loop-model holders often include a base case but expect only one copy of the variables; base-case omitters expect the function to stop on its own.

Relations

conflicts_with: A recursive function stops only when a base case returns (external)
resolved_by: A recursive function stops only when a base case returns (external)
Each recursive call has its own activation with its own variables (external)
confusable_with: programming.functions.recursion-as-loop

Alignments

progmiscon Scratch/BaseCaseNotNeeded (close-match)

Provenance

Origin: llm-drafted

Chiodini, L., Moreno Santos, I., Gallidabino, A., Tafliovich, A., Santos, A. L., & Hauswirth, M. (2021). A curated inventory of programming language misconceptions. In Proceedings of the 26th ACM Conference on Innovation and Technology in Computer Science Education (ITiCSE '21), 380-386. doi:10.1145/3430665.3456343
Inventory consulted for the misconception name and scope only; progmiscon publishes no licence for its text, so Open Misconceptions' statements and examples are written independently.
Kahney, H. (1983). What do novice programmers know about recursion? In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI '83), 235-239. doi:10.1145/800045.801618
Götschi, T., Sanders, I., & Galpin, V. (2003). Mental models of recursion. In Proceedings of the 34th SIGCSE Technical Symposium on Computer Science Education (SIGCSE '03), 346-350. doi:10.1145/611892.612004

Drafted from the cited literature for the Open Misconceptions seed pack; statement, examples and discriminators are original text. Awaiting maintainer review.

Review status

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Formats

Raw JSON
CASE 1.1 package (CFItem 09dac977-0121-45e8-8a5c-0aa059faf59c)
Source on GitHub

Cite

miscon:programming.functions.base-case-not-needed
https://open-misconceptions.github.io/miscon-data/m/programming.functions.base-case-not-needed