Code Review in C++: What to Check and How to Give Feedback for Beginners

Code Review in C++: What to Check and How to Give Feedback

Code review is one of the key stages of software development. This is especially important for C++, where memory management errors or incorrect use of the standard library can lead to serious problems. In this article, we will break down what to pay attention to when reviewing C++ code and how to give feedback that is useful, not offensive.

Why is Code Review Important for C++?

C++ is a powerful but complex language. It gives the developer a high level of control, but requires attentiveness. Typical problems: memory leaks, undefined behavior, inefficient algorithms. A good code review helps identify such errors before they reach production.

For beginner developers, code review is not just a check, but also a learning opportunity. By receiving feedback, you learn to write better quality code. By giving reviews, you learn to analyze and argue.

What to Check in C++ Code: A Checklist

To make the review systematic, use the following checklist.

1. Memory and Resource Management

This is the foundation of C++. Errors here are the most dangerous.

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• Are smart pointers used instead of raw pointers? std::unique_ptr and std::shared_ptr should be the standard. Raw pointers are only acceptable for observation (non-owning).
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• Are there any leaks? Check that every new has a corresponding delete (if smart pointers are not used).
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• Are resources released correctly? Files, sockets, mutexes should be wrapped in RAII classes.
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// Bad: raw pointer and manual management\nvoid process() {\n    int* data = new int[100];\n    // ... if an exception occurs here, there will be a leak\n    delete[] data;\n}\n\n// Good: smart pointer\nvoid process() {\n    auto data = std::make_unique<int[]>(100);\n    // memory will be freed automatically\n}

2. Type Safety and Avoiding Undefined Behavior

C++ is full of undefined behavior (UB). The reviewer must be vigilant.

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• Is there any array out-of-bounds access? Use std::array or std::vector with .at() instead of raw arrays.
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• Is type casting done correctly? Avoid C-style casts. Use static_cast, dynamic_cast, const_cast, or reinterpret_cast deliberately.
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• Are all variables initialized? Uninitialized variables are a common cause of UB.
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• Is there any signed integer overflow? In C++, this is UB.
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// Bad: C-style cast and uninitialized variable\nint* p = (int*)malloc(sizeof(int));\nint x; // not initialized\n*p = x; // UB\n\n// Good: explicit cast and initialization\nint* p = static_cast<int*>(std::malloc(sizeof(int)));\nint x = 0;\n*p = x;

3. Performance and Efficiency

You don't always need to chase speed, but obvious bottlenecks should be fixed.

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• Are objects passed by value unnecessarily? Large objects should be passed by const reference (const &).
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• Are there any unnecessary copies? Use move semantics where appropriate.
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• Is the correct container chosen? std::vector for fast index access, std::list for frequent insertions in the middle.
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• Is a virtual function called in a hot loop? This can be slow.
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// Slow: copying a large object\nvoid process(std::string s) { /* ... */ }\n\n// Fast: passing by const reference\nvoid process(c