C++ One Definition Rule (ODR): can you define the same non-inline function more than once in the same program (across translation units)?

Introduction / Context:The One Definition Rule (ODR) in C++ governs how many definitions of an entity (functions, objects, types) may appear in a program. Violating the ODR often leads to linker errors or undefined behavior. This question asks whether you may define the same (non-inline) function more than once in the same program.

Given Data / Assumptions:

• We are discussing ordinary (non-inline, non-template, non-special) functions.
• Multiple translation units are linked together to form one program.
• Header inclusion may replicate declarations, but not definitions, unless special rules apply.

Concept / Approach:

• Under the ODR, each function must have exactly one definition in the entire program (inline functions and templates have special rules).
• Multiple identical definitions of a non-inline function across translation units violate the ODR.
• Correct practice: place the function definition in a single .cpp file and declare it in headers with extern linkage as needed.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• Identical definitions / separate includes / repeated includes: All still produce multiple definitions unless the function is marked inline or is a template defined consistently, which is not the case stated.
• None of the above: Incorrect because the ODR prohibition applies.

Common Pitfalls:

• Placing non-inline function definitions in headers and including them in multiple translation units.
• Confusing declarations (allowed in many places) with definitions (must be unique).

Final Answer: