A function is a section of a program that can act on data and return a value. Every C++ program has at least one function, the
main() function called automatically when the program runs. This function can contain statements that call other functions, some of which might call others, and so on.
Each function has a name that’s used to call the function. The execution of the program branches to the first statement in that function and continues until it reaches a
return statement or the last statement of the function. At that point, ...