BCA

                                                             CATEGORY OF FUNCTION 1.Library function 2.Userdefined function LIBRARY FUNCTION It is also called predefined function or built-in or system define or fundamental or intrinsic function.This type of function is predefined by the system we cannot modify in this type of function.It has limited task.A user can only used the function but cannot change them.It means than user cannot understand the internal working of these function. For example: printf(),scanf(),clrscr(),getch() etc. NOTE: Whenever we use libray function in our program then the related header file must be included. USER-DEFINED FUNCTION The functions which are designed according to the requirement user are called User-defined function .The user can modify this type of function there task is not limited. In programming environment certain partof the logic need to create upper on function where return value is needed after performing the task. Exe

                                                               FUNCTION Afunction is a group of statements that together perform a task.Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. Afunction declaration tells the compilar about a function's name, return type, and parameters.A function definition provides the actual body of the function. The C standard library provides numerous built-in functions that your program can call.For example strcat() to concatenate two strings, memcpy()  to copy one memory location to another location, and many more functions. Why we need functions in C Functions are used because of following reasons – a) To improve the readability of code. b) Improves the reusability of the code, same function can be used in any program rather than writing the same code from scratch. c) Debugging of the code would be easier if you use functions, as errors are easy to be traced.

                  Input devices                     Keyboard Keyboard is the most common and very popular input device which helps to input data to the computer.The layout of the keyboard is like that of traditional typewriter, although there are some additional keys provided for performing additional functions.                           Mouse Mouse is the most popular pointing device.It is a very famous cursor control device having a small palm size box with a round ball at its base, which senses the movement of the mouse and sends corresponding signals to the cpu when the mouse button are pressed.                   Scanner            Scanner It is an input device, which works more like a photocopy machine.It is used when some information is available on paper and it is to be transferred to the hard disk of the computer for further manipulation . Light pen It is a pointing device similar to a pen.It is used to select a displayed menu item or draw