RubyHow-ToBeginner · 3 min read

How to Use If Else in Ruby: Simple Guide with Examples

In Ruby, use if to run code when a condition is true, and else to run code when it is false. The syntax is if condition ... else ... end. This lets your program choose between two paths based on a condition.

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Syntax

The if else statement in Ruby lets you run different code depending on a condition. It starts with if followed by a condition, then the code to run if true. The else part runs if the condition is false. Always end with end.

if condition: Checks if the condition is true.
code: Runs if condition is true.
else: Runs if condition is false.
end: Closes the if else block.

ruby

if condition
  # code if true
else
  # code if false
end

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Example

This example checks if a number is positive or not. It prints a message based on the condition.

ruby

number = 5
if number > 0
  puts "The number is positive"
else
  puts "The number is zero or negative"
end

Output

The number is positive

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Common Pitfalls

Common mistakes include forgetting the end keyword, mixing up if and else blocks, or using incorrect indentation which can confuse readers. Also, remember that Ruby treats nil and false as falsey, everything else is truthy.

ruby

wrong:
if number > 0
  puts "Positive"
else
  puts "Not positive"
# missing end

correct:
if number > 0
  puts "Positive"
else
  puts "Not positive"
end

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Quick Reference

Keyword	Purpose
if	Starts the condition check
else	Runs code if condition is false
elsif	Checks another condition if first is false
end	Ends the if else block

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Key Takeaways

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

Always close your if else block with end.

Indent your code inside if and else for clarity.

Remember Ruby treats only false and nil as falsey.

Use elsif for multiple conditions between if and else.