💻 HOW TO DEBUG YOUR CODE 🐛🔍

1️⃣ READ THE ERROR MESSAGE

Don't ignore the error.

An error message usually tells you:

👉 What went wrong

👉 Where it happened

👉 Sometimes why it happened

Example:

"NameError: name 'total' is not defined"

This tells you that Python cannot find a variable called "total".

2️⃣ CHECK THE LINE NUMBER

Most programming errors tell you where the problem occurred.

Go directly to that line.

Then check:

• Variable names

• Syntax

• Data types

• Function calls

• Missing brackets

• Incorrect indentation

3️⃣ UNDERSTAND THE ERROR TYPE

Common errors beginners encounter:

"SyntaxError" → Code doesn't follow the language syntax.

"NameError" → You used a name that hasn't been defined.

"TypeError" → An operation was performed on an incompatible data type.

"IndexError" → You tried to access an invalid index.

"KeyError" → A dictionary key doesn't exist.

"ValueError" → A value has the wrong format or isn't acceptable.

👉 Learn what common errors mean instead of simply searching for fixes.

4️⃣ CHECK YOUR ASSUMPTIONS

Sometimes your code runs without an error but produces the wrong result.

Example:

"age = "25""

You might think "age" contains a number.

But it actually contains a string.

Always ask:

👉 What type is this variable?

👉 What value does it currently contain?

5️⃣ PRINT INTERMEDIATE VALUES

When you're unsure what is happening, inspect your variables.

Example:

"print(total)"

"print(count)"

"print(average)"

This helps you understand how the values change while your program runs.

6️⃣ BREAK THE PROBLEM INTO SMALL PARTS

Don't debug 200 lines of code at once.

Separate the problem.

Instead of asking:

❌ "Why doesn't my program work?"

Ask:

✅ "Is my input correct?"

Then:

✅ "Is my calculation correct?"

Then:

✅ "Is my loop working?"

Then:

✅ "Is my output correct?"

Small questions are easier to solve.

7️⃣ CHECK YOUR LOOP

Loops are a common source of bugs.

Check:

👉 Where does the loop start?

👉 When does it stop?

👉 Is the condition correct?

👉 Is the variable being updated?

👉 Could this become an infinite loop?

Example:

"while count < 10:"

" print(count)"

" count += 1"

If "count" never changes, the loop may never end.

8️⃣ CHECK YOUR DATA TYPES

Many bugs happen because developers expect one type but receive another.

Example:

""10" + "20""

Result:

""1020""

But:

10 + 20

Result:

30

The values look similar, but their data types are different.

9️⃣ TEST WITH SIMPLE INPUT

If your program fails with complicated data, simplify it.

Instead of:

[15, 82, 43, 91, 27, 64, 10]

Try:

[1, 2, 3]

Then:

[1]

Then:

[]

Simple inputs make problems easier to identify.

🔟 TEST EDGE CASES

Always test unusual situations.

Examples:

• Empty input

• One element

• Duplicate values

• Negative numbers

• Very large numbers

• Missing values

• Invalid input

A solution isn't truly reliable until you understand how it behaves in these situations.

1️⃣1️⃣ USE A DEBUGGER

As your programs become larger, use debugging tools.

A debugger allows you to:

🔹 Pause execution

🔹 Inspect variables

🔹 Execute code step by step

🔹 Set breakpoints

🔹 Find where the logic goes wrong

This is much more powerful than adding "print()" everywhere.