Local variables and naming conventions in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of local variable assignment and usage

What is the output of this Ruby code snippet?

Ruby

def example
  number = 10
  number = number + 5
  puts number
end
example

A 15

B 10

C 5

D Error: undefined local variable

💡 Hint

Look at how the variable 'number' is updated before printing.

The variable 'number' starts at 10, then 5 is added, so the output is 15.

🧠 Conceptual

intermediate

Valid local variable names in Ruby

Which of the following is a valid local variable name in Ruby?

A _tempValue

B 2variable

C VariableName

D $globalVar

💡 Hint

Local variables must start with a lowercase letter or underscore.

In Ruby, local variables must start with a lowercase letter or underscore. '2variable' starts with a digit, 'VariableName' starts with uppercase (which is a constant), and '$globalVar' is a global variable.

🔧 Debug

advanced

Identify the error in local variable usage

What error does this Ruby code produce?

Ruby

def test
  puts value
  value = 5
end
test

A No error, prints 5

B TypeError: nil can't be coerced into Integer

C SyntaxError: unexpected local variable assignment

D NameError: undefined local variable or method `value' for main:Object

💡 Hint

Consider when local variables are initialized and when they are used.

The variable 'value' is used before it is assigned, causing a NameError.

📝 Syntax

advanced

Correct local variable assignment syntax

Which option correctly assigns a local variable in Ruby?

A localVar := 10

B localVar => 10

C localVar = 10

D localVar == 10

💡 Hint

Assignment uses a single equal sign.

In Ruby, local variables are assigned using a single equal sign '='.

🚀 Application

expert

Determine the number of local variables after execution

After running this Ruby method, how many local variables exist inside it?

Ruby

def count_vars
  a = 1
  b = 2
  if a < b
    c = a + b
  end
  d = c * 2
  return d
end
count_vars

A 3

B 4

C 2

D 1

💡 Hint

Count all variables assigned inside the method, including inside conditionals.

Variables a, b, c, and d are all assigned inside the method, so there are 4 local variables.