relationship
No. A relation is not a special type of function.
Try to be more precise; explain what you mean by the type of a function.
No. A relation is not a special type of function.
The function header. The return value is written before the name of the function. This return type must match the type of the value returned in a return statement.
you
Function
popopopopop
the return type is void
Well, it depends on what you mean by the type of a function. There are user defined functions and library functions.
The SUM function would be the most commonly used function in Excel.
Function templates are generic functions for which at least one argument must be a generic type. You cannot instantiate a generic type without knowing its actual type, so until you provide an actual type for the function, the function template cannot be instantiated. You provide an actual type simply by calling the function. If an unambiguous template exists, the compiler generates the actual function for you. At that point the function is said to have been instantiated, just as if you'd written the function by hand. If you call the function again with different types, then new instances of the function are instantiated to match those types, just as if you'd manually written the overloads yourself.
To Type