Switch
Statement:
This is a multi-directional conditional control
statement. Sometimes, there is a need in program to make choice among number of
alternatives. For making this choice, we use the switch statement.
The general
syntax is
switch(expression)
{ case constant1:
statements ;
break ;
- - - -
- - - -
case constantN:
statements ;
break,
default:
statements ;
}
Here, switch, case and default
are keywords. The ‘expression’ following the switch keyword can be any C
expression that yields an integer value or a character value. It can be value
of any integer or character variable, or a function call returning on integer,
or arithmetic, logical, relational, bitwise expression yielding integer value.
The constants following the
case keywords should be of integer or character type. These constants must be
different from each other. The statements under case can be any valid C
statements like if...else, while, for or even another switch statement. Writing
a switch statement inside another is called nesting of switches.
Firstly, the switch expression
is evaluated then value of this expression is compared one by one with every
case constant. If the value of expression matches with any case constant, then
all statements under that particular case are executed. If none of the case
constant matches with the value of the expression then the block of statements
under default is executed.
|* Program to
understand the switch control statment *|
#include<stdio.h>
main()
{ int
choice ;
printf
(“Enter your choice :” ) ;
scanf
(“%d”, & choice)
switch(choice)
{
case 1 :
printf
(“first|n”) ;
case 2 :
printf
(“second|n”) ;
case 3 :
printf
(“third|n”) ;
default
:
printf
(“wrong choice\n”) ;
}
Output:
Enter
your choice : 2
Second
Third
Wrong
Choice
Here value of choice matches
with second case so all the statements after case 2 are executed sequentially.
The statements of case 3 and default are also executed in addition to the
statements of case2. This is called falling through cases. Suppose we don’t
want the control to fall through the statements of all the cases under the
matching case, then we can use break statement.
Break
statement:
Break statement is used inside
lops and switch statements. Sometimes it becomes necessary to come out of the
loop even before the loop condition becomes false. In such a situation, break
statement is used to terminate the loop. This statement causes an immediate exit
from that loop in which this statement appears. It can be written as (i.e.
general syntax) :
break,
If a break statement is encountered inside a switch,
then all the statements following break are not executed and the control jumps
out of the switch.
/* Program to
understand the switch with break statement */
#include<stdio.h>
main()
{
int
choice ;
printf
(“Enter your choice : ”) ;
scanf
(“%d”, & choice) ;
switch
(choice)
{
case1:
print
(“First\n”) ;
break ;
/* break statement */
case2:
printf(“Second\n”)
;
break ;
case3:
printf
(Third\n”) ;
break ;
default
:
printf
(“Wrong choice\n”) ;
}
} /* End
of main() */
Output:
Enter
your choice : 2 ↵
/* Program to
perform arithmetic calculation on integers */
#include<stdio.h>
main()
{ char
op ;
int a, b
;
printf
(“Enter a number, operators and another num :”) ;
scanf
(“%d%c%d, &a, &op, &b) ;
switch
(op)
{
case ‘+’
:
printf
(“Result = %d\n”, a+b) ;
break ;
case ‘-‘
:
printf
(“Result = %d\n”, a-b) ;
case ‘*’
:
printf
(“Result = %d\n”, a*b) ;
case ‘/’
printf
(“Result = %d\n”, a/b) ;
case ‘%’
printf
(“Result = %d\n”, a%b) ;
default:
printf
(“Enter your valid operation”) ;
} /* end
of switch */
} /* end
of main() */
/* Program to
find whether the alphabet is a vowel or consonant */
#include<stdio.h>
main()
{ char
ch ;
printf
(“Enter an alphabet :” ) ;
scanf
(“%c”, &ch) ;
switch
(ch)
{
case ‘a’
: case ‘A’ :
case ‘e’
: case ‘E’ :
case ‘i’
: case ‘I’ :
case ‘o’
: case ‘O’ :
case ‘u’
: case ‘U’ :
printf
(“Alphabet is a vowel\n”) ;
break ;
default
:
printf
(“Alphabet is a constant\n”) ;
} /* end
of switch */
} * end
of main() */
Continue
statement:
The continue statement is used
to bypass the remainder of the current pass through a loop. The loop does not
terminate when a continue statement is encountered. Instead the remaining loop
statements are skipped and the computation proceeds directly to the next pass through
the loop.
The general syntax :
continue ;
/* Program to
demonstrate continue statement */
#include<stdio.h>
main()
{
int i,
num ;
printf
(“\n Enter a number :”) ;
scanf
(%d”, &num) ;
printf
(“\n The even numbers from 2 to %d are : \n”, num) ;
for
(i=1, ; i<=num ; i++)
{
if(i%2!=0)
continue
;
printf
(“\t%d”, i) ;
{ /* end
of for loop */
} / *
end of main() */
Output:
Enter a
number : 20
The even
numbers from 2 to 20 are
0
4 6
8 10 12 14 16 18 20
goto
statement:
The goto statement is used to alter the normal
sequence of program execution by unconditionally transferring control to some
other part of the program. The goto statement transfers the control to the
labeled statement somewhere in the current function.
The general syntax
of goto statement:
goto label ;
- - - - -
- - - - -
label :
statement ;
- - - - -
- - - - -
Here, label is any valid C
identifier and it is followed by a colon. Whenever, the statement goto label,
is encountered, the control is transferred to the statement that is immediately
after the label.
Generally, the use of goto statement is avoided as it
makes program illegible and unreliable. This statement is used in unique
situations like
• Branching around statements or group of statements
under certain conditions
• Jumping to the end of a loop under certain
conditions, thus bypassing the remainder of loop during current pass.
• Jumping completely out of the loop under certain
conditions, terminating the execution of a loop.
/* Program to
print whether the number is even or odd */
#include<stdio.h>
main()
{ int n
;
printf(
“Enter the number :”) ;
scanf
(“%d”, &n) ;
if (n%2
= = 0)
goto
even ;
else
goto
odd;
even :
printf
(“Number is even”) ;
goto end
;
odd :
printf
(“Number is odd”) ;
end :
printf
(“\n) ;
}
Output:
Enter
the number : 6 ↵
Number is even.
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