(i) The return value of the function is of type long.
(ii) fact is the name of the function.
(iii) The function is called with two arguments:
The first argument is of int data type.
The second argument is of double data type. 
int display(int, int) // function prototype
The above function prototype provides details about the return data type, name of the function and a list of formal parameters or arguments.

The pow() function returns base raised to the power of exponent. If any argument passed to pow() is long double, the return type is promoted to long double. If not, the return type is double. The pow() function takes two arguments.
(i) base- the base value
(ii) exponent - exponent of the base
Example :
cout <<pow(5,2);
output
25

The strcmp () function takes two arguments: string 1 and string 2. It compares the contents of string 1 and string 2 lexicographically.
The strcmp() function returns a:
(i) Positive value if the first differing character in string 1 is greater than the corresponding character in string 2. (ASCII values are compared).
(ii) Negative value if the first differing character in string 1 is less than the corresponding character in string 2.
(iii) 0 if string 1 and string 2 are equal.

C++ provides a rich collection of functions ready to be used for various tasks. The tasks to be perfornned by each of these are already written, debugged and compiled, their definitions alone are grouped and stored in files called header files. Such ready-touse sub programs are called pre-defined functions or build-in functions.