Why Don\'t C Compilers Generate `operator==()` and `operator!=()`?-C++-php.cn

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Why Don\'t C Compilers Generate `operator==()` and `operator!=()`?

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Dec 04, 2024 am 07:08 AM

Why Don't C Compilers Generate `operator==()` and `operator!=()`?

Compiler-Generated Operator Overloading: Why No Operator==() or Operator!=() for C Classes?

C compilers readily generate common operators like default constructors, copy and move constructors, destructors, and assignment operators (operator=). However, they do not offer the same convenience for comparison operators (operator==, operator!=). This absence raises questions about the compiler's inability to perform member-by-member comparisons for simple classes.

Compiler Design Decisions

The decision not to provide compiler-generated comparison operators stems from concerns about default copy construction. In his book "The Design and Evolution of C ," Bjarne Stroustrup expresses reservations about default copy operations, citing their potential for unintended and problematic behavior.

Backward Compatibility and Language Evolution

The legacy of C significantly influenced C , inheriting default assignment and copy constructors for backwards compatibility. Despite Stroustrup's reluctance, these features became widely adopted. The focus on maintaining compatibility likely precluded the introduction of default comparison operators, which could have potential complexities compared to the simpler operations that were provided.

Conflicting Design Goals

Compiler-generated comparison operators would enable easier object comparison but could conflict with the principle of enforcing explicit operator overloading in C . This design principle encourages developers to thoughtfully consider the behavior of their operators, ensuring consistency and avoiding unintended behavior.

Developer Considerations

For developers who value compiler automation, the absence of default comparison operators requires manual definition. However, this provides an opportunity to tailor comparison behavior specifically to the class's needs, considering factors such as memory allocation and object semantics.

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