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
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
}
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
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.
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;
}