The document discusses functions in C++. It defines a function as a block of code that performs a specific task. There are two types of functions: built-in functions provided by the language and user-defined functions created by the programmer. The components of a function include the function header, body, parameters, return type, local variables, and return statement. Functions can pass arguments either by value or by reference. The document provides examples of built-in and user-defined functions as well as examples demonstrating call by value and call by reference.

1. F2037 - PROGRAMMING
FUNDAMENTAL WITH C++
Unit 5.1 - Understand The Use Of Function

2. LEARNING OUTCOME
At the end of this module, students should be able to:
 Define a function
 Explain the following types of function:Built-in
function, User-defined function
 Describe the components of function :
a. Function header
b. Function body
c. Local variable
d. Return statement
e. Parameters declaration list
f. Function prototypes
 Identify the function calls : call by value, call by
reference
 Write program using functions

3. INTRODUCTION TO FUNCTION
 A function is a set of statements that performs a
specific task.
 It can be called from any section in the program
and executed.
 The main advantage in using functions is that the
number of lines in a program can be reduced.
 One long program willl be divided into smaller parts
and each of these parts is programmed separately

4. TYPES OF FUNCTIONS
 built-in function - system function.
 User-defined function - Created by the users for
their requirements.

5. Built-in Function User-defined Function
strlen(“fadzlina”) float purata(float x, float y)
atof(s) void panggilan(void)
pow(x, y) char response(char ch)

6. BUILT-IN FUNCTION
#include<cmath>
#include<iostream>
using namespace std;
void main()
{
double d=100.0, d1=100.5, d2=22.0;
//find the square root of the number
cout<<"nSquarer Root of" << d<<" is = "<<sqrt(d)<<endl;
//find log 10 of the number
cout<<"nlog10 for" << d<<" is = "<<log10(d)<<endl;
//compute power of two number
cout<<"n" << d<<" to the power of "<<d2;
cout<<" is = " <<pow(d,d2)<<"nn";
}

8. USER-DEFINED FUNCTION
#include <iostream>
using namespace std;
void kira_luasSegiempat(int, int);
void main()
{
int p,l;
cout<<"Masukkan nilai panjang dan lebar: ";
cin>>p>>l;
kira_luasSegiempat(p,l);
}
void kira_luasSegiempat(int panjang, int lebar)
{
double luas;
luas = panjang * lebar;
cout<<"Luas segiempat :"<<luas <<endl;
}

10. COMPONENTS OF FUNCTION
a) Function header
b) Function body
c) Local variable
d) Return statement
e) Parameters declaration list
f) Function prototypes

11. COMPONENTS OF FUNCTION
Function Header
 Has three main parts
 The name of the function
 The parameters of the function enclosed in
paranthesis
 Return value type
Function Body
 What ever is written with in { } in the above
example is the body of the function.

12. COMPONENTS OF FUNCTION
Function prototype
 The prototype of a function provides the basic
information about a function which tells the compiler
that the function is used correctly or not. It contains
the same information as the function header
contains.
Function definition
 A function must be defined before it can be used

13. COMPONENTS OF FUNCTION
Local variable
 Variable declared inside main() or function
Call Function
 Call another function by passing value or reference
Return statement (return)
 Return the control back to the function that invoked
it

14. Parameter list
 List of parameters that can be passed to the
function

15. COMPONENTS OF FUNCTION
#include <iostream>
using namespace std;
int prt(int); //Function prototype
int main() //Define function main()
{
int x = 12; //Declaration
cout << prt(x); //Calling function
return 0; //return 0 to situation
}
Parameter list
int prt(int y) //Function header & Function definition
{
return y; //Return value //Function body
}

17. FUNCTION DECLARATION
 Syntax:
function_type function_name (parameter-list)
{
variable declaration;
……
return expression;
}

18. FUNCTION DECLARATION
 function_type = type of data in C++
 function_name = name of function
 parameter-list  passing parameter value when invoked
 return  return value or control

19. IDENTIFY FUNCTION CALLS
1. Call by value
2. Call by reference

20. CALL BY VALUE
#include <iostream>
using namespace std;
int main()
{
void max_min(int, int);
int x =2,y=3;
max_min(x,y);
cout << "x: " << x;
cout << "ny: " << y;
return 0;
}
void max_min(int x, int y)
{
x= x*x;
y= y*y;
}

22. CALL BY REFERENCE
#include <iostream>
using namespace std;
int main()
{
void max_min(int&, int&);
int x=8,y=1;
max_min(x,y);
cout << "x: " << x;
cout << "ny: " << y;
return 0;
}
void max_min(int& x, int& y)
{
x= x*x;
y= y*y;
}

24. IN CLASS EXERCISE
 By using a function, write a program that able to
receive two double numbers and calculate sum
for that numbers (hint: use void function).

26. SUMMARY
 Function is a component of the program written
to perform a specific task.
 By using functions, the code written once can be
used many times anywhere in the program.
 As the program is segregated into different
smaller modules, it is very easy to correct the
errors.

27. #include<iostream>
using namespace std;
void kira_jumlah ( ); //fungsi prototype
void main ()
{
kira_jumlah ();
system(“pause”);
}

28. void kira_jumlah ( )
{
int num_1, num_2, JUMLAH;
cout<<“Sila masukan 2 integer :”;
cin>>num_1>>num_2;
JUMLAH=num_1 + num_2;
cout<<“
}

29. FUNGSI YANG TIDAK MEMULANGKAN NILAI
TETAPI MENERIMA NILAI
#include<iostream>
using namespace std;
void kira_jumlah ( int, int ); //fungsi prototype
void main ()
{
int num_1, num_2;
cout<<“Sila masukan 2 integer :”;
cin>>num_1>>num_2;
kira_jumlah (num_1,num_2);
system(“pause”);
}

30. void kira_jumlah ( int num_1, int num_2) )
{
int JUMLAH;
JUMLAH=num_1 + num_2;
cout<<“JUMLAH 2 integer adalah : “ << JUMLAH;
}