Parameters with default values in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a parameter with a default value in Ruby?

A parameter with a default value is a method parameter that has a preset value. If no argument is given when calling the method, Ruby uses this default value.

beginner

How do you define a method with a default parameter in Ruby?

You assign a value to the parameter in the method definition, like def greet(name = "Friend"). If no argument is passed, "Friend" is used.

beginner

What happens if you call a Ruby method with a default parameter and provide an argument?

The provided argument replaces the default value for that call. The method uses the argument you give instead of the default.

intermediate

Can you mix parameters with and without default values in Ruby methods?

Yes, you can. Parameters without default values should come first, followed by those with default values to avoid errors.

beginner

Example: What does this method print?<br>

def say(message = "Hello")
  puts message
end

say
say("Hi")

It prints:<br>

Hello
Hi

<br>First call uses the default "Hello". Second call uses the argument "Hi".

In Ruby, how do you set a default value for a method parameter?

A By setting the value inside the method body

B By assigning a value in the method definition, like <code>def m(param = 5)</code>

C By calling the method with no arguments

D By using a global variable

Default values are set by assigning them in the method definition parameters.

What happens if you call a Ruby method with a default parameter but provide an argument?

A The default value is ignored and the argument is used

B An error occurs

C The method uses the default value anyway

D The method ignores the argument

The argument you provide replaces the default value for that call.

Which order should parameters be in when mixing default and non-default values in Ruby?

A Default parameters first, then non-default

B Only default parameters are allowed

C Order does not matter

D Non-default parameters first, then default parameters

Non-default parameters must come before default parameters to avoid syntax errors.

What will this Ruby code print?<br>

def greet(name = "Guest")
  puts "Hi, #{name}!"
end
greet("Alice")

A Hi, Alice!

B Hi, Guest!

C Hi, !

D Error

The argument "Alice" replaces the default "Guest".

Why are default parameters useful in Ruby methods?

A They force all arguments to be provided

B They make methods slower

C They allow methods to be called with fewer arguments

D They prevent method calls

Default parameters let you skip arguments and still have meaningful values.

Explain how to use parameters with default values in Ruby methods and why they are helpful.

Think about how you can make a method flexible with fewer required inputs.

Describe the correct order of parameters when mixing default and non-default values in Ruby methods and why order matters.

Consider how Ruby matches arguments to parameters.