1. Lab 8
User Defined Function

2. What is a function? main() { . } examples: cos(a); sin(a); pow(a,b);
{.. }

3. Using a function Declaring name and type of function
#include <stdio.h>
output function (input)
void main (void)
{……….
function()
……….. .}
{…. …… …}
Declaring name and type of function
Using the function within main()
Writing the actual function

4. Function example #include <stdio.h> #include <math.h>
void main (void) {
int x=10,n=3,r;
printf("This line will appear on your screen\n");
r=pow(x,n);
printf("\nr = %d\n\n",r); }
function f1()
function f2()

5. no variable values are exchanged between main() and f1()
Function example: f1()
#include <stdio.h>
#include <math.h>
void f1 (void);
void main (void)
{int x=10,n=3,r;
f1();
r=pow(x,n);
printf("\nr = %d\n\n",r); }
void f1 (void) {
printf("This line will appear on your screen\n");
no variable values are exchanged between main() and f1()

6. Function example: f2() #include <stdio.h>
#include <math.h>
void f1 (void);
void f2 (int a, int b);
void main (void)
{int x=10,n=3;
f1();
f2(x,n); }
void f1 (void)
{ printf("This line will appear on your screen\n"); }
void f2 (int a, int b)
{ int r;
r=pow(a,b);
printf("\nr = %d\n\n",r); }
a and b are two integer inputs to function f2()
f2() is given two integer inputs
r is defined

7. Function example: f2() contd
#include <stdio.h>
#include <math.h>
void f1 (void);
int f2 (int a, int b);
void main (void)
{int x=10,n=3,result;
f1();
result=f2(x,n);
printf("\nr = %d\n\n",result);}
void f1 (void)
{ printf("This line will appear on your screen\n"); }
int f2 (int a, int b)
{ int r;
r=pow(a,b);
Return r;}
value of r calculated by f2() is stored in result
f2() returns an integer
value of r is returned to main()

8. Factorial
Write a program to calculate the factorial of an inputted number n
n! = n * n-1 * n-2 * …..* 2 * 1
Examples:
5! = 120
4! = 24

9. Binomial Coefficient
Write a program that calculates the binomial coefficient
Three factorials are needed
Calculate factorials through a function called factorial()