C Arrays vs. std::vectors: Is There a Significant Performance Difference?

Performance Comparison of C Arrays and std::vectors

C arrays have been discouraged for modern projects, but do they exhibit significant performance discrepancies compared to std::vectors?

Use of Dynamic C Arrays

Dynamic C arrays using "new" are highly discouraged due to the need for manual tracking, deletion, and cleanup, leading to potential memory leaks and errors.

Static C Arrays

Static C arrays on the stack are also discouraged due to the lack of range checking and the loss of size information when passing them as pointers. Instead, std::array provides a size function and iterators for improved safety.

std::vector vs. Native C Arrays

Analyzing assembly code generated for operations like indexing, dereferencing, and incrementing reveals that:

• Vector indexing is equivalent to pointer indexing.
• Vector iterator dereferencing is equivalent to pointer dereferencing.
• Vector iterator incrementing is equivalent to pointer incrementing.

Exception

An exception exists when allocating new arrays of non-class objects without a user-defined constructor and without initial element initialization. In such cases, new-allocated arrays can be advantageous as std::vector initializes elements during construction, incurring some overhead.

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