The document discusses the switch statement in C++. It provides examples of using switch to check conditions, display text for different cases, handle multiple cases with the same code, and make a basic calculator program. It also notes some limitations of switch, such as not allowing float expressions or variable expressions as cases. The document aims to explain how to properly structure switch statements and provide real-world examples of their use.

1. Lab No. 3
saqib.rasheed@mail.au.edu.pk
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2. Write a program to check whether a triangle is
valid or not, when the three angles of the
triangle are entered through the keyboard. A
triangle is valid if the sum of all the three
Angles is equal to 180 degrees
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3. switch statement
The control statement that allows
us to make a decision from the
number of choices is called a
switch

4. switch ( variable name )
{
case „a‟ :
statements;
case „b‟ :
statements;
case „c‟ :
statements;
…
}

5. switch statements
switch ( grade)
{
case „A‟ :
cout << “ Excellent ” ;
case „B‟ :
cout << “ Very Good ” ;
case „C‟ :
…
…
}

6. switch statements
case „A‟ :
cout << “ Excellent ” ;
…
…

7. switch ( grade)
{
case „A‟ :
cout << “ Excellent ” ;
case „B‟ :
cout << “ Very Good ” ;
case „C‟ :
cout << “Good ” ;
case „D‟ :
cout << “ Poor ” ;
case „F‟ :
cout << “ Fail ” ;
}

8. break;

9. switch ( grade )
{
case „A‟ :
cout << “ Excellent ” ;
break ;
case „B‟ :
cout << “ Very Good ” ;
break ;
case „C‟ :
cout << “Good ” ;
break ;
case „D‟ :
cout << “ Poor ” ;
break ;
case „F‟ :
cout << “ Fail ” ;
break ;
}

10. default :
default :
cout << “ Please Enter Grade from
„A‟ to „D‟ or „F‟ “ ;

11. Flow Chart of switch statement
switch (grade)
case ‘A’ :
Display
“Excellent”
case ‘B’ :
Display
“Very Good”
…
Default :
“……..”

12. int i = 2 ;
switch ( i )
{
case 1 :
cout<<"I am in case 1 n"; break;
case 2 :
cout<<"I am in case 2 n"; break;
case 3 :
cout<<"I am in case 3 n"; break;
default :
cout<<"I am in default n";
}
Output
I am in case 2

13. if (x == 1)
switch (x)
{
{
cout << "x is 1";
case 1:
}
cout << "x is 1";
else if (x == 2)
break;
{ case 2:
cout << "x is 2"; cout << "x is 2";
} break;
else default:
{ cout << "value of x unknown";
cout << "value of x unknown"; }
}

14. There are some things that you simply cannot
do with a switch. These are:
 A float expression cannot be tested using a
switch
 Cases can never have variable expressions
(for example it is wrong to say case a +3 : )
 Multiple cases cannot use same expressions.
Thus the following switch is illegal:
switch ( a )
{
case 3.2 :
...
case 1 + 2 :
...
}

15. int day;
cout<<"Eneter Day Number";
cin>>day;
switch (day)
{
case 1 : cout << "nSunday";
break;
case 2 : cout << "nMonday";
break;
case 3 : cout << "nTuesday";
break;
case 4 : cout << "nWednesday";
break;
case 5 : cout << "nThursday";
break;
case 6 : cout << "nFriday";
break;
case 7 : cout << "nSaturday";
break;
default : cout << "nNot an allowable day number";
break;
}

16. switch (day)
{
case 1 :
case 7 :
cout << "This is a weekend day"; Break
1
break;
case 2 :
case 3 :
case 4 :
case 5 :
case 6 : cout << "This is a weekday";
Break
break; 2
default : cout << "Not a legal day"; break;
}

17. char ch ;
cout<< "Enter any of the alphabet a, b, or c ";
cin>>ch;
switch ( ch )
{
case 'a' : case 'A' :
cout<<"a is an apple" ; break ;
case 'b' :
case 'B' :
cout<<"b as in brain";
break ;
case 'c' : case 'C' :
cout<<"c as in cookie"; break ;
default :
cout<<"wish you knew what are alphabets" ;
}

18.  Yesand no. Yes, because it offers a better
way of writing programs as compared to if,
and no because in certain situations we are
left with no choice but to use if. The
disadvantage of switch is that one cannot
have a case in a switch which looks like:
 case i <= 20 :

19.  compiler generates a jump table for a switch
during compilation
 during execution it simply refers the jump
table to decide which case should be
executed .
 if-elses are slower because they are
evaluated at execution time

20. Make a calculator using switch statement
 It should take two numbers from user.
 Ask the user the function to perform
 Display the result
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21. Que
Write a menu driven program program in C++
using switch statement that contain option as
under.( The Menu should )
Enetr 1--> To Find Largest Number Among Three Variables.
Enetr 2--> To Find ODD or EVEN
Enetr 3--> To Find Condition of Water
Enetr 4--> To Find Grade Of Student
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