Find & Fix Variable Mistakes in Python | Practice & Progress

Sharpen your Python debugging skills with ‘Find & Fix’ exercises for variable mistakes—naming errors, assignment issues, scope bugs—perfect for hands-on learning!.

Topic: variables

🧪 Fix & Find Questions

🟢 Beginner Fix & Find

1. Fix the invalid variable name:

   global-var = 10
   print(global-var)
   

   Hint: 💡 Python variable names cannot contain hyphens.

   🔍 View Issue & Fixed Solution

   Issue: Hyphens are interpreted as subtraction operators.

   ✅ Fixed Solution

   global_var = 10
   print(global_var)
   

   ---

2. Fix the variable assignment error:

   print(message)
   message = "Hello"
   

   Hint: 💡 Variables must be defined before use.

   🔍 View Issue & Fixed Solution

   Issue: Trying to access `message` before assignment.

   ✅ Fixed Solution

   message = "Hello"
   print(message)
   

   ---

3. Fix the None comparison:

   result = None
   if result == None:  # Works but non-idiomatic
       print("Empty")
   

   Hint: 💡 Python has a dedicated operator for `None` checks.

   🔍 View Issue & Fixed Solution

   Issue: Should use identity comparison (`is`) for `None`.

   ✅ Fixed Solution

   result = None
   if result is None:
       print("Empty")
   

   ---

🟡 Intermediate Fix & Find

1. Fix the type confusion bug:

   price = "10"
   total = price * 2
   print(total)  # Outputs "1010" (unexpected)
   

   Hint: 💡 Strings and numbers behave differently with `*`.

   🔍 View Issue & Fixed Solution

   Issue: Dynamic typing allows the operation but produces undesired string concatenation.

   ✅ Fixed Solution

   price = 10  # or int("10")
   total = price * 2
   print(total)  # Outputs 20
   

   ---

2. Fix the None-related crash:

   def get_user():
       return None
   
   user = get_user()
   print(user.upper())  # AttributeError
   

   Hint: 💡 Methods can't be called on `None`.

   🔍 View Issue & Fixed Solution

   Issue: Attempting to call `.upper()` on a `None` value.

   ✅ Fixed Solution

   def get_user():
       return None
   
   user = get_user()
   if user is not None:
       print(user.upper())
   else:
       print("No user found")
   

   ---

🔴 Advanced Fix & Find

1. Fix the dynamic typing pitfall:

   def add(a, b):
       return a + b
   
   print(add(5, 3))     # 8
   print(add("5", "3")) # "53" (unexpected for numbers)
   

   Hint: 💡 The `+` operator has different behaviors per type.

   🔍 View Issue & Fixed Solution

   Issue: Function works differently with strings vs numbers.

   ✅ Fixed Solution

   def add(a, b):
       return int(a) + int(b)
   

   ---

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