The if-else control structure in C++ provides a way to perform decision-making operations. If the condition inside the 'if' block evaluates to true, the 'if' block of code is executed; otherwise, the 'else' block is executed, if present. It can be used to check multiple conditions in sequence by nesting or using "else if".

shared_ptr uses reference counting, which means it keeps a count of the number of shared_ptr objects referring to the same memory location. When this count drops to zero (meaning no shared pointers are referring to the object), the memory is automatically deallocated.

In C++, the forward slash (/) operator is used for division. When used between two integers, it gives the quotient of the division.

The std::list::remove function has a linear time complexity O(n). This is because it traverses the list once, removing all elements that match a specified value. As it potentially examines all elements, the complexity is linear.

Propagation refers to the process where after an exception is thrown, it travels up the call stack until it's caught by an appropriate catch block or, if uncaught, the program terminates.

In a for loop, the initial statement is typically used for initialization purposes. This is where variables, often loop counters, are initialized before the loop begins its execution.

While C++ uses classes and objects to encapsulate data and behavior, there are cases where you might want an external function (not belonging to the class) to access the private or protected members of the class. This is where friend functions come into play. They provide an exception to the usual encapsulation rules.

The diamond problem is a complication that arises from multiple inheritance when two classes B and C inherit from A, and class D inherits from both B and C. If there is a method in A that B and C have overridden, and D does not override it, then which version of the method does D inherit: that of B, or that of C? This ambiguity can be resolved in C++ using virtual inheritance, ensuring that only one instance of the base class exists in the derived class.

In C++, the size of long double is compiler-dependent. However, according to the C++ standard, it is at least 8 bytes or the size of a double, whichever is greater. Some compilers may allocate more.

Excessive use of templates can result in code that has much larger compiled sizes than equivalent non-template code. This phenomenon, where the binary gets bloated due to templates, is known as template bloat.