Using pdb
for Debugging
Debugging is an important part of writing code, and Python has a built-in tool called pdb
to help with this.
What is pdb
?
pdb
is Python’s interactive debugger. It lets you pause your code, inspect variables, and step through the code line by line to find out what’s going wrong.
Setting Breakpoints
Breakpoints allow you to pause your code at specific points to see what’s happening at that moment.
Example:
In your Python script, you can set a breakpoint like this:
import pdb; pdb.set_trace()
def add(a, b):
return a + b
result = add(2, 3)
print(result)
When you run this script, it will pause before returning the result, allowing you to inspect variables and step through the code.
Stepping Through Code
pdb
lets you execute your code line by line to see what happens at each step.
Example:
Using the same script, once pdb
pauses execution, you can step through the code.
(pdb) n # 'n' is for next line
(pdb) p a # 'p' is for print
2
(pdb) p b
3
(pdb) c # 'c' is for continue
Inspecting and Modifying Variables
You can check and change the values of variables at any point during execution.
Example:
While debugging, you might find the value of a
is not as expected. You can modify it.
(pdb) p a
2
(pdb) a = 5
(pdb) p a
5
Evaluating Expressions
pdb
lets you run Python expressions interactively, so you can test code snippets in real-time.
Example:
(pdb) p a + b
8
Why Use pdb
?
Using pdb
gives you a deeper understanding of your code’s execution flow compared to just using print
statements. Instead of scattering print
statements throughout your code, you can use pdb
to explore and diagnose issues interactively. This makes debugging more efficient and helps you find the root cause of problems more effectively.