summary

1. Function

2. Introduction
 Use of function
 Calling a formula defined by user
 Input & Output depends on type of function
 Not included in main body
 Can be called many times

3. Function Prototype
 After #include<iostream>
 Before int main()
Example 1
# include <iostream>
void FindMax(int, int); //prototype
using namespace std;
int main()

4. 4
Calling Function
Example 2
int main()
{
int num1, num2;
cout<<"Please enter a number :";
cin>> num1;
cout<<"Great!nPlease enter a second number :";
cin>> num2;
FindMax(num1, num2); //calling function
system ("PAUSE");
return 0;
}

5. Defining Function
 Outside main body
Example 3
void FindMax(int x, int y){
int maxNum;
if (x>=y)
maxNum=x;
else
maxNum=y;
cout<<"Maximum number is : "<<maxNum <<endl;
}

6. Using reference variable
 The Prototype:
 void FindMax(double, double, double&);
 The Calling:
 FindMax(num1, num2, maxNum);
 The Defining:
 void FindMax(double x, double y, double& maxNum)
 maxNum: a value edited in main function

7. • Compare Example 2
Example 4
int main()
{
double num1, num2, maxNum;
cout<<"Please enter a number :";
cin>> num1;
cout<<"Great!nPlease enter a second number :";
cin>> num2;
FindMax(num1, num2, maxNum); //calling
system ("PAUSE");
return 0;
}
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8. Looping Function
 Just insert function in loop to call as needed
 Looping with returned value :
 Declare return value
 Send value to function
 Write a loop
 Example :
 Using while loop to keep comparing numbers

9. Example 5
char next;
while(true){
cout<<"n('n' to exit')Compare with next number? :";
cin>> next;
if(next=='n')
break;
cout<<"Okay!nPlease enter the next number :";
cin>> num1;
num2 = maxNum;
FindMax(num1, num2, maxNum);
}

10. END