If, elsif, else statements in Ruby - Step-by-Step Execution

Concept Flow - If, elsif, else statements

Start

↓

Check if condition

|Yes↓

Execute if block

↓

End

No↓

Check elsif condition

|Yes↓

Execute elsif block

↓

End

No↓

Execute else block

↓

End

The program checks the if condition first. If true, it runs the if block. If false, it checks the elsif condition. If that is true, it runs the elsif block. Otherwise, it runs the else block.

Execution Sample

Ruby

number = 7
if number < 5
  puts "Less than 5"
elsif number == 7
  puts "Equals 7"
else
  puts "Other number"
end

This code checks a number and prints a message depending on its value.

Execution Table

Step	Condition Checked	Condition Result	Branch Taken	Output
1	number < 5	false	No
2	number == 7	true	Yes	Equals 7
3	else	N/A	No

💡 The elsif condition is true, so the elsif block runs and the rest is skipped.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
number	7	7	7	7

Key Moments - 2 Insights

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

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

What happens if the first if condition is true?

If the first if condition is true, the program runs the if block and skips checking the elsif and else blocks, as shown by the flow in concept_flow.

Visual Quiz - 3 Questions

Look at the execution table, what is the output at step 2?

A Equals 7

B Less than 5

C Other number

D No output

💡 Hint

Check the 'Output' column in execution_table row 2.

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

A Step 1

B Step 2

C Step 3

D It never skips the else block

💡 Hint

Look at the 'Branch Taken' column in execution_table rows 2 and 3.

If number was 3, which branch would run according to the execution flow?

A else block

B elsif block

C if block

D No block runs

💡 Hint

Refer to the condition 'number < 5' in execution_table step 1.

Concept Snapshot

if condition
  # code if true
elsif condition
  # code if elsif true
else
  # code if none true
end

Checks conditions in order and runs the first true block only.

Full Transcript

This visual execution shows how Ruby's if, elsif, else statements work. The program starts by checking the if condition. If it is true, it runs that block and skips the rest. If false, it checks the elsif condition. If that is true, it runs the elsif block and skips else. If none are true, it runs the else block. The example code checks if a number is less than 5, equals 7, or something else, and prints a message accordingly. The execution table traces each condition check and the branch taken. The variable tracker shows the number stays the same. Key moments clarify why else is skipped when elsif is true and what happens if the first if is true. The quiz tests understanding of output and flow decisions.