Switch-case statements in MATLAB

Introduction

Switch-case statements help you choose what to do based on different possible values. It makes your code cleaner and easier to read than many if-else checks.

When you want to run different code depending on a variable's value.

When you have many options to check and want to avoid long if-else chains.

When you want to handle specific cases clearly and separately.

When you want a default action if none of the cases match.

Syntax

MATLAB

switch expression
    case value1
        % code to run if expression == value1
    case value2
        % code to run if expression == value2
    otherwise
        % code to run if no case matches
end

The expression is what you check against each case value.

The otherwise part is optional and runs if no cases match.

Examples

This checks the value of day. If it is 1, it prints Monday; if 2, Tuesday; otherwise, it prints Other day.

MATLAB

switch day
    case 1
        disp('Monday')
    case 2
        disp('Tuesday')
    otherwise
        disp('Other day')
end

You can group multiple values in one case using a cell array like {'red', 'blue'}.

MATLAB

switch color
    case {'red', 'blue'}
        disp('Primary color')
    case 'green'
        disp('Secondary color')
end

Sample Program

This program checks the value of choice. Since it is 3, it prints the message for option 3.

MATLAB

choice = 3;
switch choice
    case 1
        disp('You chose option 1')
    case 2
        disp('You chose option 2')
    case 3
        disp('You chose option 3')
    otherwise
        disp('Invalid choice')
end

Important Notes

Each case must be unique; MATLAB matches the first one that fits.

Use otherwise to catch unexpected values and avoid errors.

Summary

Switch-case helps select code to run based on a value.

It is cleaner than many if-else statements.

Use otherwise for default actions.

Practice

1. What is the main purpose of a switch-case statement in MATLAB?

easy

A. To repeat a block of code multiple times

B. To create a new variable

C. To define a function

D. To execute different blocks of code based on the value of a variable

Solution

1. Step 1: Understand the role of switch-case

   A switch-case statement chooses which code to run depending on a variable's value.

2. Step 2: Compare with other options

   Repeating code is done by loops, defining functions is different, and creating variables is unrelated.

3. Final Answer:

   To execute different blocks of code based on the value of a variable -> Option D

4. Quick Check:

   Switch-case selects code by value [OK]

Hint: Switch-case runs code based on one variable's value [OK]

Common Mistakes:

• Confusing switch-case with loops
• Thinking switch-case defines functions
• Assuming switch-case creates variables

2. Which of the following is the correct syntax to start a switch-case block in MATLAB?

easy

A. switch variable

B. case variable

C. switch-case(variable)

D. switch = variable

Solution

1. Step 1: Recall switch-case syntax

   The switch statement starts with the keyword switch followed by the variable name.

2. Step 2: Check each option

   switch variable matches correct syntax. Options A, B, and C are invalid MATLAB syntax for switch.

3. Final Answer:

   switch variable -> Option A

4. Quick Check:

   Start switch with 'switch variable' [OK]

Hint: Start switch with 'switch' plus variable name [OK]

Common Mistakes:

• Using parentheses after switch
• Writing 'case' instead of 'switch' to start
• Assigning variable with '=' in switch

3. What will be the output of this MATLAB code?

color = 'green';
switch color
    case 'red'
        disp('Stop')
    case 'green'
        disp('Go')
    otherwise
        disp('Wait')
end

medium

A. Go

B. Wait

C. Stop

D. Error

Solution

1. Step 1: Check the value of variable 'color'

   The variable color is set to 'green'.

2. Step 2: Match the case in switch

   The switch checks cases: 'red' (no), 'green' (yes), so it runs disp('Go').

3. Final Answer:

   Go -> Option A

4. Quick Check:

   color='green' triggers 'Go' [OK]

Hint: Match variable value to case labels to find output [OK]

Common Mistakes:

• Choosing output from wrong case
• Ignoring the otherwise block
• Assuming syntax error

4. Identify the error in this MATLAB switch-case code:

value = 10;
switch value
case 5
    disp('Five')
case 10
    disp('Ten')
case
    disp('Other')
end

medium

A. Incorrect variable name in switch

B. Missing 'otherwise' keyword for default case

C. Missing 'end' statement

D. Case values must be strings

Solution

1. Step 1: Review the case statements

   The last case has no value and no keyword 'otherwise'. MATLAB requires 'otherwise' for default.

2. Step 2: Check syntax rules

   Case values can be numbers, 'end' is present, variable name is correct.

3. Final Answer:

   Missing 'otherwise' keyword for default case -> Option B

4. Quick Check:

   Default case needs 'otherwise' keyword [OK]

Hint: Use 'otherwise' for default case, not empty case [OK]

Common Mistakes:

• Leaving case without value or otherwise
• Thinking 'end' is missing
• Believing case values must be strings

5. You want to write a MATLAB switch-case that prints 'Weekend' for days 'Saturday' and 'Sunday', 'Weekday' for Monday to Friday, and 'Invalid' otherwise. Which code correctly implements this?

hard

A. switch day
case ['Saturday', 'Sunday']
disp('Weekend')
case ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday']
disp('Weekday')
otherwise
disp('Invalid')
end

B. switch day
case 'Saturday' || 'Sunday'
disp('Weekend')
case 'Monday' || 'Tuesday' || 'Wednesday' || 'Thursday' || 'Friday'
disp('Weekday')
otherwise
disp('Invalid')
end

C. switch day
case {'Saturday', 'Sunday'}
disp('Weekend')
case {'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'}
disp('Weekday')
otherwise
disp('Invalid')
end

D. switch day
case 'Saturday', 'Sunday'
disp('Weekend')
case 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'
disp('Weekday')
otherwise
disp('Invalid')
end

Solution

1. Step 1: Understand how to group cases in MATLAB

   MATLAB allows grouping multiple values in a cell array inside case, like {'Saturday', 'Sunday'}.

2. Step 2: Check each option's syntax

   switch day case {'Saturday', 'Sunday'} disp('Weekend') case {'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'} disp('Weekday') otherwise disp('Invalid') end uses correct cell arrays for grouping. switch day case 'Saturday' || 'Sunday' disp('Weekend') case 'Monday' || 'Tuesday' || 'Wednesday' || 'Thursday' || 'Friday' disp('Weekday') otherwise disp('Invalid') end uses invalid '||' inside case. switch day case ['Saturday', 'Sunday'] disp('Weekend') case ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'] disp('Weekday') otherwise disp('Invalid') end uses square brackets which is wrong for strings. switch day case 'Saturday', 'Sunday' disp('Weekend') case 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday' disp('Weekday') otherwise disp('Invalid') end uses commas incorrectly.

3. Final Answer:

   Code with cell arrays for grouped cases -> Option C

4. Quick Check:

   Group cases with cell arrays {} in switch-case [OK]

Hint: Group multiple cases using curly braces {} [OK]

Common Mistakes:

• Using || inside case labels
• Using square brackets for string groups
• Separating cases with commas instead of cell arrays