What is a function? Functions are nothing but sub-programs of a program. Is a part of a program which performs a particular task as desired by the programmer. It can be called anywhere in the program. S. Kiran PGT(Comp. Science), KV, Malleswaram

Functions exhibit the feature of MODULARITY in OOP (Object Oriented programming). What is Modularity? The act of breaking up larger programs into smaller unit is called modularity. S. Kiran PGT(Comp. Science), KV, Malleswaram

Advantages of using Functions Easier to maintain, update and debug. Enhances readability of the program Reusability of code S. Kiran PGT(Comp. Science), KV, Malleswaram

TYPES OF FUNCTIONS BUILT – IN FUNCTIONS USER DEFINED FUNCTIONS S. Kiran PGT(Comp. Science), KV, Malleswaram

BUILT – IN FUNCTIONS These are part of the compiler package, which are defined in the standard library files also called header files. For e.g.., string.h header file contains definition for the following functions. strlen(), strcmp(), strrev () etc. S. Kiran PGT(Comp. Science), KV, Malleswaram

USER DEFINED FUNCTIONS Are functions defined by the programmer. That is YOU. S. Kiran PGT(Comp. Science), KV, Malleswaram

FUNCTION DEFINITION A function must be defined before it is used anywhere in the program. Three important things that must be remembered 1. Function prototype 2. Function call 3. Function Definition S. Kiran PGT(Comp. Science), KV, Malleswaram

FUNCTION PROTOTYPE It has the following parts 1. Return type 2. Function Name 3. Parameters or Argument list For e.g.: int sum ( int x, int y) ; Return type Name Argument List Function prototype must end with a semi colon S. Kiran PGT(Comp. Science), KV, Malleswaram

FUNCTION DEFINITION AND CALL #include int square ( int n) #include { void main()return n x n; {} clrscr(); int square(int); int a, s; cout<<“Enter value for a”; cin>>a; s = square(a); cout<<“Square of given no. is”<<s; getch(); } S. Kiran PGT(Comp. Science), KV, Malleswaram prototype Func. call Function definition

S. Kiran PGT(Comp. Science), KV, Malleswaram

Note: A function prototype is not required if the function definition appears before its calling function Program Program S. Kiran PGT(Comp. Science), KV, Malleswaram

RECAPITULATION S. Kiran PGT(Comp. Science), KV, Malleswaram

Which feature of OOP does function exhibit? List the advantages of using functions? Name the different types of functions. Three things to remember in a function ______ What does function prototype tell the compiler? What is meant by return type? S. Kiran PGT(Comp. Science), KV, Malleswaram