MatlabHow-ToBeginner · 3 min read

How to Use If Else in MATLAB: Syntax and Examples

In MATLAB, use if to check a condition and execute code when true, and else to run code when the condition is false. The basic structure is if condition ... elseif condition ... else ... end.

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Syntax

The if statement tests a condition. If true, it runs the code inside. You can add elseif to check more conditions and else for the default case. Always end with end.

if condition: Checks if the condition is true.
elseif condition: Checks another condition if the first is false.
else: Runs if all above conditions are false.
end: Closes the if block.

matlab

if condition
    % code if condition is true
elseif another_condition
    % code if another_condition is true
else
    % code if none of the above conditions are true
end

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Example

This example checks a number and prints if it is positive, zero, or negative using if, elseif, and else.

matlab

number = -5;

if number > 0
    disp('The number is positive.')
elseif number == 0
    disp('The number is zero.')
else
    disp('The number is negative.')
end

Output

The number is negative.

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Common Pitfalls

Common mistakes include forgetting the end statement, using assignment = instead of comparison ==, and mixing up elseif spelling.

Also, conditions must return logical true or false, not values like strings or numbers directly.

matlab

%% Wrong: missing end
if x > 0
    disp('Positive')

%% Wrong: assignment instead of comparison
if x = 5
    disp('x is 5')
end

%% Correct version
if x == 5
    disp('x is 5')
end

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Quick Reference

Keyword	Purpose
if	Start a condition check
elseif	Check another condition if previous is false
else	Run if all conditions are false
end	Close the if block

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Key Takeaways

Use if to run code when a condition is true and else for the false case.

Always close your if block with end.

Use == for comparison, not = which is assignment.

You can check multiple conditions using elseif.

Conditions must evaluate to true or false logical values.