[C++] Difference between pointer and reference, value passing and reference passing, function pointer, smart pointer
A pointer is a variable that stores an address (position in memory space). When a variable is declared, memory for the variable is allocated and placed in the memory space. However, immediately after the variable declaration, the pointer contains an undefined value and it is not known where it points. The address of the variable can be obtained by preceding the variable name with the `&` symbol.
