What are some C++ related idioms, misconceptions, and gotchas that you've learnt from experience?

Question

What are some C++ related idioms, misconceptions, and gotchas that you\'ve learnt from experience?

An example:

class A
{
  public: 
  char s[1024];
  cha         


        

Answer 1

A few things that usually trip people up:

std::cout << a << a++ << --a;
i = ++i;

The above lines are both undefined.

void foo(bar* b1, bar* b2);

int main() {
  foo(shared_ptr(new bar()), shared_ptr(new bar()));
}

The above may leak memory.

int* arr = new int[10];
arr + 11;

This results in undefined behavior.

As for idioms, my favorite is RAII. Allocate objects on the stack, which guarantees that the destructor is called when the object goes out of scope, preventing resource leaks.