LC

Implement a Python Built-in Function in C

hard7/8

Understand CPython's Memory Allocator: obmalloc Understand CPython's Reference Counting

Language

Compiler

2.0s Limit 256MB

Implementation

Write a C program showing how to implement a built-in function.

Requirements:

Show PyCFunction signature and METH_VARARGS flag
Implement a fast string reversal function in C
Show argument parsing with PyArg_ParseTuple (format "s")
Show error handling with PyErr_SetString for non-string args
Return a new string PyObject from the C function
Print the conceptual implementation flow
Show how the function would be registered in builtins_methods

Why This Matters

len(), sum(), and abs() are real entries in CPython's Python/bltinmodule.c registered exactly the way you're building here, calling internal C API functions like PyObject_Size() and PyNumber_Absolute(). Implementing your own built-in teaches the same PyArg_ParseTuple-then-PyErr_SetString discipline that guards every function CPython exposes to Python code.

Hints

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Sample validation

Sample case for Run. Submit grades this sample plus all hidden tests.

main.c

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