C++

Quick Reference

Critical Rules

• Raw new without delete leaks — use std::unique_ptr or std::make_unique
• Returning reference to local — undefined behavior, object destroyed on return
• == for C-strings compares pointers — use std::string or strcmp()
• Signed integer overflow is UB — not wrap-around like unsigned
• Virtual destructor required in base class — otherwise derived destructor skipped
• std::move doesn't move — it casts to rvalue, enabling move semantics
• Moved-from object valid but unspecified — don't use without reassigning
• Data race on non-atomic is UB — use std::mutex or std::atomic
• vector is not a real container — returns proxy, use deque
• map[key] inserts default if missing — use find() or contains() to check
• Braced init {} prevents narrowing — int x{3.5} errors, int x(3.5) truncates
• Iterator invalidation on push_back — vector may relocate, invalidating iterators
• string_view doesn't own data — underlying string must outlive the view