Passing parameters by reference gives a function direct access to the original data. This can be risky as inadvertent changes in the function can lead to unintended modifications to the data. Care must be taken to ensure the integrity of the data and to avoid unexpected side effects. This risk doesn't exist when passing parameters by value since the function works with a copy of the data.

A constructor is a special member function of a class that is executed whenever a new object of that class is created. Its primary role is to initialize the attributes or properties of the class, ensuring that the object starts its life in a controlled state.

"Const correctness" is a concept in C++ that ensures certain functions or methods don't modify the data they're working on. By declaring pointers or references as 'const', you're ensuring that they can't be used to modify the underlying data. This provides a level of safety against unintended side-effects and potential sources of memory corruption.

A tail-recursive function has its recursive call as the last action, which means the function doesn't need to hold onto its context or any other state between recursive calls. This nature allows it to be easily translated into an iterative structure, primarily using loops.

In C++, if the new operator fails to allocate the requested memory, it throws an exception of type bad_alloc. This is especially useful in situations where robustness is necessary, as it allows programs to handle memory allocation failures gracefully.

The break statement is primarily used to terminate loops and switch statements. Using a break outside these constructs, like directly inside a function without a loop or switch, would result in a compilation error as it wouldn't have a clear context to operate within.

The ~ operator is the bitwise NOT operator in C++. It inverts each bit of a number, changing 1s to 0s and 0s to 1s. & is the bitwise AND, | is the bitwise OR, and ^ is the bitwise XOR operator.

In C++, the "std" stands for the standard namespace. A namespace is a declarative region that provides a scope to the identifiers inside it. Using the "std" namespace, we can access features of the C++ Standard Library without prepending their names with std:: each time.

Using exception specifications like throw(type) can lead to unpredictable behavior if a different type of exception is thrown. In C++11 and later, these exception specifications are deprecated in favor of noexcept. If a function with a dynamic exception specification throws an exception not listed, it will call std::unexpected().

The standard library in C++ provides a set of predefined classes that represent standard exception types. Developers can leverage these classes to catch common errors or even derive their own custom exception types from these base classes.