This document discusses switch-case statements in C programming. It explains that switch-case statements provide a way to implement decision making when a variable is tested for multiple possible integral values. Each case represents a different action. The document provides the syntax of switch-case statements and explains that all code within a matched case will execute until a break statement. It includes an example program that uses a switch-case statement to output a message based on a letter grade input.

1. Switch…Case Statement
Prakash Khaire
B V Patel Inst. of BMC & IT, Gopalvidyanagar

2. Switch Multiple Selection
Structure
A multiple selection structure is useful when an
●
algorithm contains a series of decisions in which
a variable or expression is tested separately for
one of several possible integral values.
●Each integral value represents a different action
to be taken in the algorithm.
●C provides the switch multiple selection structure
to implement this type of decision making.

3. Switch-Case Structures
The switch - case syntax is:
●
switch (integer expression test value)
{
case case _1_fixed_value :
action(s) ;
case case_2_fixed_value :
action(s) ;
default :
action(s) ;
}

4. Switch-Case Structures
The switch is the "controlling expression"
●
■Can only be used with constant integer expressions.
■Remember, a single character is a small positive
integer.
■The expression appears in ( )
The case is a "label"
●
■The label must be followed by a " : "
■Braces, { }, not required around statements

5. Switch-Case Structures
●Unlike if-else if-else structures, when the
value in a case matches the test value, all of
the actions in the rest of the structure take
place.
●This is shown in the following program where
the user enters a value that matches the first
case and every action in the structure is
executed.

6. A Sample Program to Illustrate
Switch-Case
/* This program associates a letter grade with a
message appropriate to the score.
*/
#include <stdio.h>
int main ( )
{
char grade ;
printf ("Enter your current letter graden") ;
grade = getchar ( ) ;
Winter Quarter
Winter Quarter Lect 9 P. *

7. A Sample Program to Illustrate
Switch-Case
case ('c') :
case ('C') :
printf ("Better get to work.n") ;
case ('d') :
case ('D') :
printf ("You are in trouble.n") ;
default :
printf ("You are failing!!n") ;
} /* End of switch-case structure */
} /* End of main program */
Winter Quarter
Winter Quarter Lect 9 P. *

8. Switch-Case Structures
break ;
●The problems with the previous program can be
corrected by use of the break statement.
●It can be used in either a repetition structure or a
selection structure to break out of (that is, to exit
from) the structure.
●The syntax is:
break ;
●The following program is the previous one with the
addition of the break statements.

9. Why Use a switch Statement?
●A nested if-else structure is just as efficient
as a switch statement.
●However, a switch statement may be easier
to read.
●Also, it is easier to add new cases to a switch
statement than to a nested if-else structure.