Explain User defined function and How to call the User defined function
Need of User defined function
It makes program easier to understand, debug and test.
It saves both time and space.
It facilitates top-down modular programming. In this
programming style, the high level logic of the overall problem is
solved first while the details of each lower-level functions are
addressed later.
The length of a source program can be reduced by using
functions at appropriate places.
It is easy to locate and isolate a faulty function for further
investigation.
A function may be used by many other programs.
In order to make use of a user-defined function, we need
to establish three elements that are related to functions :
Function definition
Function call
Function declaration
The function definition is an independent program module that is
specially written to implement the requirements of the function.
In order to use this function we need to invoke it at a required place in the program. This is known as function call. The program
(or a function) that calls the function is referred to as the
calling program or calling function.
The calling program should declare any function (like declaration of a variable) that is to be used later in the program. This is known as function declaration or function prototype.