FUNCTIONS IN C++ PART7|HOW FUNCTION IS CALLED|FUNCTION PROTOTYPE|FUNCTION ARGUMENTS|DEFAULT ARGUMEN смотреть онлайн

This video explains three topics:
How functions are to be called?
Prototype of functions
Arguments of functions and Default arguments

How functions are to be called?
No function other than main() is executed automatically.
All the other functions will be executed only when they are called.
Calling function and called functions
Example :
void sum1();
int product( int, int);
prototype of functions
A function prototype is the declaration of a function by which compiler is provided with the information about the function such as :
the name of the function,
its return type,
the number and type of arguments, and
its accessibility.
This information is essential for the compiler to verify the correctness of the function call in the program.
Syntax :
data_type function_name(argument_list);
In the prototype, the argument names need not be specified.
Number and type of arguments must be specified.
Like a variable declaration, a function must be declared before it is used in the program. If a function is defined before it is used in the program, there is no need to declare the function separately.
Note: The position of the prototype differs in the accessibility of the function.
Arguments of functions
We know that functions have arguments or parameters for getting data for processing.
The constants, variables or expressions used in the function call are known as actual (original) arguments.

The variables used in the function definition as arguments are known as formal arguments.

If variables are used in function prototype, they are known as dummy arguments.
We have seen that functions can be defined with arguments assigned with initial values. The initialized formal arguments are called default arguments which allow the programmer to call a function with different number of arguments.
It is important to note that all the default arguments must be placed from the right to the left in the argument list.
When a function is called, actual arguments are
passed to the formal arguments from left onwards.