Using pdb and ipdb Interactive Debuggers in Python

In Python, several interactive debuggers such as pdb and ipdb help debug complex issues by allowing line‑by‑line execution, variable inspection, breakpoints, and code navigation.

1. Using the pdb debugger:

import pdb

def divide(x, y):
    result = x / y
    return result

pdb.set_trace()  # set breakpoint
divide(10, 0)

2. Common pdb commands:

- n: execute next line
- s: step into function call
- c: continue until next breakpoint
- l: list current source context
- p <variable>: print variable value
- q: quit debugger

3. Using the ipdb debugger:

import ipdb

def divide(x, y):
    result = x / y
    return result

ipdb.set_trace()
divide(10, 0)

4. ipdb commands are similar to pdb commands.

5. Tracing code execution flow:

import pdb

def foo():
    print("foo")
    bar()

def bar():
    print("bar")

pdb.set_trace()
foo()

6. Viewing variable values:

import pdb

def foo():
    x = 10
    pdb.set_trace()
    y = x + 5
    print(y)

foo()

7. Jumping to a specific line:

import pdb

def foo():
    print("foo")
    pdb.set_trace()
    print("bar")

foo()

8. Setting conditional breakpoints:

import pdb

def foo():
    for i in range(10):
        pdb.set_trace()  # breakpoint
        print(i)

foo()

9. Entering the debugger on exception:

import pdb

def divide(x, y):
    try:
        result = x / y
    except ZeroDivisionError:
        pdb.post_mortem()  # enter debugger on exception
    return result

divide(10, 0)

10. Remote debugging:

import pdb
import remote_pdb

def foo():
    print("foo")
    remote_pdb.set_trace(host='0.0.0.0', port=4444)  # start remote debugger
    print("bar")

foo()

These examples illustrate common usages of pdb and ipdb ; they can be adapted and extended to suit specific debugging needs, improving development efficiency and code quality.