If-elseif-else statements in MATLAB - Step-by-Step Execution

Concept Flow - If-elseif-else statements

Start

↓

Check if condition1

|Yes↓

Execute block1

↓

End

No↓

Check if condition2

|Yes↓

Execute block2

↓

End

No↓

Execute else block

↓

End

The program checks conditions in order. It runs the first true block and skips the rest. If none are true, it runs the else block.

Execution Sample

MATLAB

x = 7;
if x < 5
    y = 10;
elseif x < 10
    y = 20;
else
    y = 30;
end

This code sets y based on the value of x using if-elseif-else.

Execution Table

Step	Condition Checked	Condition Result	Action Taken	Variable y Value
1	x < 5	7 < 5 is false	Skip if block	undefined
2	x < 10	7 < 10 is true	Execute elseif block: y = 20	20
3	Else block	Skipped because previous condition true	No action	20

💡 Execution stops after first true condition block runs (elseif block).

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
x	7	7	7	7
y	undefined	undefined	20	20

Key Moments - 2 Insights

Why does the else block not run even though it is last?

Because the elseif condition was true at step 2, the program runs that block and skips the else block, as shown in the execution_table row 3.

What happens if the first if condition is true?

If the first if condition is true, the program runs that block and skips all elseif and else blocks, stopping after step 1.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of y after step 2?

A 10

B 30

C 20

D undefined

💡 Hint

Check the 'Variable y Value' column in row 2 of the execution_table.

At which step does the program decide to skip the else block?

A Step 1

B Step 2

C Step 3

D Never

💡 Hint

Look at the 'Action Taken' column in step 2 where the elseif block runs.

If x was 3, how would the execution_table change at step 1?

A Condition would be true and y would be set to 10

B Condition would be false and y would be set to 20

C Condition would be false and y would be set to 30

D No change

💡 Hint

Check the condition 'x < 5' and what happens when it is true in the execution_table.

Concept Snapshot

If-elseif-else statements check conditions in order.
Syntax:
if condition1
  % code
elseif condition2
  % code
else
  % code
end
Only the first true condition block runs.
If none true, else runs.

Full Transcript

This visual execution shows how if-elseif-else statements work in MATLAB. The program checks the first condition. If false, it checks the next. When it finds a true condition, it runs that block and skips the rest. If none are true, it runs the else block. Variables change only in the executed block. This helps control program flow based on conditions.