2. At the end of this presentation, students will be
able to:
• Understand selection control structures
• Describe the structure and working of simple if
statements
• Describe the structure and working of nested if
statements
• Describe the structure and working of switch
statements
3. Statements executed one by one.
Simplest
Example :
int x = 5; [S1]
int power = x*x; [S2]
cout << “n” << power; [S3]
Entry S1 S2 S3 Exit
4. C++ supports two types of program
control:
• selection control structures
• looping control structures
5. Purpose:
• to evaluate expressions/condition
• to direct the execution of the program (depending on the
result of the evaluation).
The most commonly used selection statements
are:
• if statement
• if-else statement
• nested-if statement
• switch statement
6. Used to execute a set of statements when
the given condition is satisfied.
Syntax
if (<condition>)
{
<Conditional statements>;
}
Conditional statements within the block are
executed when the condition in the if
statement is satisfied.
7. false
condition
Conditional statement
true
Next statement
8. Example:
if (age > 21)
cout << “n Anda layak mengundi”;
9. false
age > 21
Anda layak mengundi
true
Next statement
10. Program InputValue.cpp illustrates the
execution of a simple if statement. The
program checks whether the given
number is greater than 100.
12. #include <iostream>
using namespace std;
int main()
{
int num;
cout << "Enter integer number: ";
cin >> num;
if(num<100)
cout<<"Number is less than 100"<<endl;
return 0;
}
13.
14. Executes the set of statements in if block,
when the given condition is satisfied.
Executes the statements in the else block,
when the condition is not satisfied.
Syntax
if (<condition>)
{
<Conditional statements1>;
}
else
{
<Conditional statements2>;
}
15. true false
condition
Conditional statement in else
Conditional statement in if body
body
Next statement
16. Example:
if (E4162 == ‘L’)
cout << “n Anda lulus”;
else
cout << “n Anda gagal”;
17. true false
E4162 == ‘L’
Anda lulus Anda gagal
Next statement
18. Program Checks.cpp illustrates the use of
the if-else statement. This program accepts a
number, checks whether it is less than 0 and
displays an appropriate message.
19. start
Declare: number variable
Read number
true false
number<0
Print Print
“Negative” “Positive”
end
20. #include <iostream>
using namespace std;
int main()
{
int num;
cout << "Enter integer number: ";
cin >> num;
if(num<0)
cout<<"Negative"<<endl;
else
cout<<"Positive"<<endl;
return 0;
}
21. 1. Accept a number from the keyboard
and check whether it is dividable by 5
(if else).
Hint: Use the modulus operator, %, to
check the divisibility.
22. #include <iostream>
using namespace std;
int main()
{
int no;
cout<<"Enter integer number: ";
cin>>no;
if(no%5==0)
cout<<"dividable by 5"<<endl;
else
cout<<"undividable by 5"<<endl;
return 0;
}
23. 2. Accept two integer numbers from the
keyboard and find the highest among
them.
24. #include<iostream>
using namespace std;
int main()
{
int no1,no2;
cout<<"Enter two integer number: ";
cin>>no1>>no2;
if(no1>no2)
cout<<"Number 1 is highest than number 2"<<endl;
else
cout<<"Number 2 is highest than number 1"<<endl;
return 0;
}
25. The if statements written within the body of
another if statement to test multiple
conditions is called nested if.
Syntax
if (<Condition 1>)
{
if (<Condition 2>)
{
<Conditional statements1>;
}
else
{
<Conditional statements2>; Inner if
}
} condition Outer if
else
{ condition
<Conditional statements3>;
}
27. The program Highest.cpp illustrates the
use of nested if statements. The program
accepts three integers from the user and
finds the highest among the three.
28. #include <iostream>
using namespace std; if(x>y)
{
int main() if(x>z)
{ cout<<x<<" is the highest";
int x,y,z; else
cout<<z<<" is the highest";
cout<<"Enter x: "; }
cin>>x; else
cout<<"Enter y: "; {
cin>>y; if (y>z)
cout<<"Enter z: "; cout<<y<<" is the highest";
cin>>z; else
cout<<z<<" is the highest";
}
return 0;
}
29. #include <iostream>
using namespace std;
int main()
{
int x,y,z;
cout<<"Enter x: ";
cin>>x;
cout<<"Enter y: ";
cin>>y;
cout<<"Enter z: ";
cin>>z;
if(x>y&&x>z)
cout<<x<<" is the highest";
else if (y>x&&y>z)
cout<<y<<" is the highest";
else
cout<<z<<" is the highest";
return 0;
}
30. #include <iostream>
using namespace std;
int main()
{
int a,b,c;
cout<<"Enter a: ";
cin>>a;
cout<<"Enter b: ";
cin>>b;
cout<<"Enter c: ";
cin>>c;
if(a>c&&b>c){
if(a>b)
cout<<a<<" is the highest";
else
cout<<b<<" is the highest";
}
else{
if(c>a&&c>b)
cout<<c<<" is the highest";
else
cout<<b<<" is the highest";
}
return 0;
}
32. Note that the first line does not end with a
semicolon.
The curly brackets are necessary only if
there are several statements.
33. Switch statement is C++'s multi-way
branch
Allows to specify a number of different
cases, rather than simply true or false
Switch statement requires an expression
after the word switch and then it jumps to
the statement whose case matches the
expression
A break statement passes the control
outside switch structure.
34. Syntax
switch (expression)
{
case expression_1 :
statement sequence;
break;
case expression_2 :
statement sequence;
break;
…………..
case expression_n :
statement sequence;
break;
default :
statement sequence;
}
36. Example:
int main()
{
char pilih;
cout << “n Menu Utaman”;
cout << “ M = Masukkan duit n”;
cout << “ K = Keluarkan duitn”;
cout << “ E = Exitn”;
cout << “ Pilihan anda: “;
cin >> pilih;
switch (pilih)
{
case ‘M’ : cout << “Sila tambah duit anda”;break;
case ‘K’ : cout << “Hanya boleh keluar duit”;break;
case ‘E’ : cout << “Keluar dari Menu Utama”;break;
default : cout << “Pilihan yang salah”;
}
}
37. Program SwitchDemo.cpp illustrates
switch case execution. In the program,
the switch takes an integer value as
input and displays the month based on
the integer entered.
38. #include <iostream>
using namespace std;
int main()
{
int month;
cout<<"Enter number: ";
cin>>month;
switch (month)
{
case 1: cout<<"January";
break;
case 2: cout<<"February";
break;
case 3: cout<<"March";
break;
case 4: cout<<"April";
break;
default: cout<<"wrong choice";
}
return 0;
}
39. 1. Write a program to accept number of a
day for the week and print the day
1 – Sunday 5 – Thursday
2 – Monday 6 – Friday
3 – Tuesday 7 – Saturday
4 - Wednesday
40. #include <iostream> case 5: cout<<"Thursday";
using namespace std;
break;
int main() case 6: cout<<"Friday";
{
int day; break;
case 7: cout<<"Saturday";
cout<<"Enter number: "; break;
cin>>day;
default: cout<<"wrong
switch (day) choice";
{ }
case 1: cout<<"Sunday";
break; return 0;
case 2: cout<<"Monday"; }
break;
case 3: cout<<"Tuesday";
break;
case 4: cout<<"Wednesday";
break;
41. Write a program that able to check either
a character is a vowel or not by using
switch statements and if else statement
42. #include <iostream>
using namespace std;
int main()
{
case 'o':
char ch;
case 'O': cout<<"Vowel";
break;
cout<<"Enter character: ";
cin>>ch; case 'u':
case 'U': cout<<"Vowel";
switch (ch) break;
{ default: cout<<"Not vowel";
case 'a': }
case 'A': cout<<"Vowel"; return 0;
break; }
case 'e':
case 'E': cout<<"Vowel";
break;
case 'i':
case 'I': cout<<"Vowel";
break;
43. #include<iostream>
using namespace std;
void main()
{
char ch;
cout<<"Enter character: ";
cin>>ch;
if(ch=='a'||ch=='A'||ch=='e'||ch=='E'||ch=='i'
||ch=='I'||ch=='o'||ch=='O'||ch=='u'||ch=='U')
cout<< ch << " is a voweln";
else
cout<< ch << " is not a voweln";
}
44. In this presentation, you learnt the following:
Program controls are used to change the
sequential flow of a program.
The two types of program controls are
selection control structures and looping
control structures
In C++, the selection control structures
include if and switch statements.
