1. Presentation on function in 'c-language' by- Sanju & Amit

2. function Defination:- function is a self-contained block of program that performs a coherent task of some kinds. Function is also called as modular programming.

4. User define function

6. Scanf( )

9. Function definition

10. Function call A function call is an expression containing a simple type name and a parenthesized argument list. The argument list can contain any number of expressions separated by commas. It can also be empty. For example: res= sum ( a , b); prime(&no);

11. Function definition In C user- written functions should normally be declared prior to its use to allow compiler to perform type checking on arguments used in its call statement. Syntex- Return_data_type function_name (data_type Var_name, …..);

15. it tells it how many parameters there are.

16. Argument – passing of values b/w the main program and the function takes place through arguments. Formal and actual argument- The actual arguments are the arguments with which the function can be called. Simply function call contains actual arguments. // Call func with actual arguments i and j. func( i, j ); -The formal arguments are the arguments with which the function can be defined. function defination contains formal arguments void Func( int i ); // Function prototype … Func( 7 ); // Execute function call

17. CALL BY VALUE AND CALL BY REFERENCE Call by value- Whenever we called a function and passed something to it we have always passed the ‘values’ of variables to the called function. Such function calls are called ‘calls by value. in this context we are working on copies of actual argument.

19. swap ( int x, int y )

20. {

21. int t ;

22. t = x ;

23. x = y ;

24. y = t ;

25. printf ( " x = %d y = %d", x, y ) ;

26. }

27. The output of the above program would be:

28. x = 20 y = 10

29. Call by refrence- An argument passing convention where the address of an argument variable is passed to a function or procedure as opposed to passing the value of the argument expression.

30. Int sum(int *,int *); void main() { int i=10, j=20; K=sum(&i,&j); Printf(“%d”,k); } Int sum(int *a, int *b) { int c; C=*a+*b; return( c ); }

31. Recursion A function is called recursive if a statement with in the body of the function calls the same function. Sometimes called circular definition. Recursion is thus the process of defining something in terms of itself.

32. Main() { int a, fact; printf(“ enter any number”); Scanf(“%d”, &a); fact = rec (a); Printf(“factorial value=%d”,fact); } int rec (int x) { int f ; if (x==1) return(1); else f=x*rec(x-1); return (f); }

35. It also reduces the Time to run a program. In other way,Its directly proportional to Complexity.

36. Its easy to find-out the errors due to the blocks made as function definition outside the main function.

37. Return statement The return statement terminates the execution of a function and returns control to the calling function. Execution resumes in the calling function at the point immediately following the call. r eturn expression ; return; The default return type is int.

38. Thank you