Menu driven
programming
Whenever you go to hotel then you will order items available in menu
card. You made order by your choice. Like this we create a program designed
with menu and user can enter his/her choice and will get output.
switch - case
statement
Switch is very useful
for designing menu driven programs.
It is similar to if statement but only the difference is
switch execute result by checking value of single variable pass to it.
It supports multi-way
decision statement. It allows user to choose a statement among several
alternatives.
The switch statement
tests the value and then executes the result through different cases. At a time
only one case gets executed because every case ends with break
statement.
The default
part of switch is executed only when none of the case is satisfied.
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switch(expression)
{
case value1:
statement;
break;
case value2:
statement;
break;
case value3:
statement;
break;
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case valuen:
statement;
break;
default:
statement;
}
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break Statement
We have already use
break statement with switch. This break statement can be use with any looping
structure. When a break statement is encountered inside a loop, the loop gets
terminated and program control is transferred to the statement immediately
after the loop.
Let us see the
example for easily understanding of switch statement.
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//Prog to perform
mathmatical operations.
#include<stdio.h>
#include<conio.h>
void main()
{
int no1,no2,add,mul,sub;
float div;
clrscr();
printf("\nEnter any two numbers");
scanf("%d%d",&no1,&no2);
add = no1 + no2;
mul = no1 * no2;
sub = no1 - no2;
div = no1 / no2;
printf("\nAddition = %d",add);
printf("\nSubstraction = %d",sub);
printf("\nMultiplication =
%d",mul);
printf("\nDivision = %f",div);
getch();
}
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In this program we
will get output as:
Enter any two numbers
20
5
Addition = 25
Subtraction=15
Multiplication = 100
Division = 4.0
That is if we only
want to check addition then also we got all things. Now let convert this
program to menu driven program by using switch then we will enter our own
choice for output.
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//program using
switch statement
#include<stdio.h>
#include<conio.h>
void main()
{
int no1,no2,choice;
clrscr();
printf("\nEnter two numbers");
scanf("%d%d",&no1,&no2);
printf("\n=================================="); //menu list
printf("\n1 . Addition");
printf("\n2 . Subtraction");
printf("\n3 . Multiplication");
printf("\n4 . Division");
printf("\n5 . Exit");
printf("\n===================================");
printf("\nEnter your choice: "); //accepts choice from user
scanf("%d",&choice);
switch(choice) //switch starts
working by checking value of choice
{
case 1:
printf("\nAddition = %d",
no1+no2);
break;
case 2:
printf("\nSubtraction =
%d",no1-no2);
break;
case 3:
printf("\nMultiplication =
%d",(no1+no2)/2);
break;
case 4:
printf("\nDivision =
%d",no1/no2);
break;
case 5:
exit(0); //library
function for exiting program
default :
//optional
printf("\nWrong
Entry");
}
getch();
}
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o/p:
Enter two numbers
20
5
1 . Addition
2 . Subtraction
3 . Multiplication
4 . Division
5
. Exit
Enter your choice: 3
Multiplication =
100
//You
will continue by inputting different choices
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Once you executed
above program then you will find that after executing single case your program
gets terminate. But if you want to continue program un till you select exit
case then it is possible by using goto
statement.
goto statement
It supports
unconditional branching. A goto unconditionally transfers the program control
from one point to another point within the program. It uses a label in order to
identify the place where the program control needs to transfer.
In above program we
first include label at the from
where we want to repeat menu. Goto statement will place outside the switch.
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//program using
switch statement
#include<stdio.h>
#include<conio.h>
void main()
{
int no1,no2,choice;
clrscr();
printf("\nEnter two numbers");
scanf("%d%d",&no1,&no2);
//mathmenu is a label
- program will repeat from this point
mathmenu:printf("\n=================================="); //menu list
printf("\n1 . Addition");
printf("\n2 . Subtraction");
printf("\n3 . Multiplication");
printf("\n4 . Division");
printf("\n5 . Exit");
printf("\n===================================");
printf("\nEnter your choice: "); //accepts choice from user
scanf("%d",&choice);
switch(choice) //switch starts
working by checking value of choice
{
case 1:
printf("\nAddition = %d",
no1+no2);
break;
case 2:
printf("\nSubtraction =
%d",no1-no2);
break;
case 3:
printf("\nMultiplication =
%d",(no1+no2)/2);
break;
case 4:
printf("\nDivision =
%d",no1/no2);
break;
case 5:
exit(0); //library
function for exiting program
default :
printf("\nWrong
Entry");
}
goto mathmenu; //label will
jump on mathmenu and continue execution till you select exit case
getch();
}
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Following program is
to calculate bonus of employee by given grade by using switch statement.
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//prog to calculate
bonus of emplyoee
#include<stdio.h>
#include<conio.h>
#define p printf //define
shorthand character p for printf and s for scanf
#define s scanf
void main()
{
int ecode,exp,sal;
char ename[10],dept[10],grd;
float bon,netsal;
clrscr();
p("\nEnter employees code: ");
s("%d",&ecode);
p("\nEnter employees name: ");
s("%s",&ename);
p("\nEnter employees department: ");
s("%s",&dept);
p("\nEnter employees experience: ");
s("%d",&exp);
p("\nEnter employees basic salary: ");
s("%d",&sal);
p("\nEnter employees grade: ");
flushall(); //library
function used for scanning single character
s("%c",&grd);
if(exp>=2)
{
switch(grd)
{
case 'A':
bon = sal * 0.3;
break;
case 'B':
bon = sal * 0.2;
break;
case 'C':
bon = sal * 0.1;
break;
case 'D':
bon = sal * 0.05;
break;
default:
bon = sal * 0.02;
} //switch
closed
} //if closed
else
bon = 0;
netsal = sal + bon;
p("\nBonus = %.2f",bon);
p("\nNet Salary = %.2f",netsal);
getch();
}
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o/p:
Enter employees
code: 1
Enter employees
name: Sachin
Enter employees
department: Marketing
Enter employees
experience: 10
Enter employees
basic salary: 8000
Enter employees
grade: B
Bonus = 1600.00
Net Salary = 9600.00
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