Chapter 9: Exception Handling & Debugging

try:
    number = int(input("Enter a number: "))
    result = 100 / number
    print("Result:", result)

except ValueError:
    print("Please enter a valid number.")

except ZeroDivisionError:
    print("Number cannot be zero.")

try:
    file = open("pdtc_report.txt", "r", encoding="utf-8")
    content = file.read()

except FileNotFoundError:
    print("Report file not found.")

else:
    print("File read successfully.")
    print(content)

finally:
    print("Automation step completed.")

from pathlib import Path
import pandas as pd

input_file = Path("business_transactions.xlsx")

try:
    if not input_file.exists():
        raise FileNotFoundError("Input Excel file is missing.")

    df = pd.read_excel(input_file)
    print("Excel file loaded successfully.")
    print(df.head())

except FileNotFoundError as error:
    print("Automation stopped:", error)

except Exception as error:
    print("Unexpected error:", error)

import logging

logging.basicConfig(
    filename="automation_log.txt",
    level=logging.INFO,
    format="%(asctime)s - %(levelname)s - %(message)s"
)

logging.info("Automation started")

try:
    total = 100 / 5
    logging.info("Calculation completed successfully")

except Exception as error:
    logging.error("Automation failed: %s", error)

logging.info("Automation finished")

import pyautogui
from datetime import datetime

try:
    raise Exception("Sample automation failure")

except Exception as error:
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    screenshot_file = "error_screenshot_" + timestamp + ".png"

    pyautogui.screenshot().save(screenshot_file)

    print("Error:", error)
    print("Screenshot saved:", screenshot_file)

from selenium import webdriver
from datetime import datetime

driver = webdriver.Chrome()

try:
    driver.get("https://example.com")
    raise Exception("Sample web automation error")

except Exception as error:
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    driver.save_screenshot("web_error_" + timestamp + ".png")
    print("Error screenshot captured.")

finally:
    driver.quit()

amount = "1200"

print("Before conversion:", amount)

amount = float(amount)

print("After conversion:", amount)

department = "Finance"
amount = 1200

breakpoint()

total = amount * 1.06

print(department, total)

import time

def unreliable_step():
    print("Trying automation step...")
    # Replace this with real automation logic.
    raise Exception("Temporary failure")

max_attempts = 3

for attempt in range(1, max_attempts + 1):
    try:
        unreliable_step()
        print("Step completed successfully.")
        break

    except Exception as error:
        print("Attempt", attempt, "failed:", error)

        if attempt == max_attempts:
            print("Maximum attempts reached. Escalate to human user.")
        else:
            time.sleep(2)

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.common.exceptions import NoSuchElementException, TimeoutException

driver = webdriver.Chrome()

try:
    driver.get("https://example.com")

    button = driver.find_element(By.ID, "submitBtn")
    button.click()

except NoSuchElementException:
    print("Button not found. Check element ID or page structure.")
    driver.save_screenshot("missing_element.png")

except TimeoutException:
    print("Page took too long to load.")

finally:
    driver.quit()

import pandas as pd
from pathlib import Path

required_columns = ["Date", "Department", "Amount", "Status"]
file_path = Path("business_transactions.xlsx")

try:
    if not file_path.exists():
        raise FileNotFoundError("Excel file does not exist.")

    df = pd.read_excel(file_path)

    missing = [col for col in required_columns if col not in df.columns]

    if missing:
        raise ValueError("Missing columns: " + str(missing))

    print("Validation successful. Bot can continue.")

except Exception as error:
    print("Validation failed:", error)

import pandas as pd

data = {
    "Name": ["Amin", "Mei Ling", "Ravi"],
    "Amount": [1200, -50, None]
}

df = pd.DataFrame(data)

errors = df[(df["Amount"].isna()) | (df["Amount"] <= 0)]

errors.to_excel("automation_error_report.xlsx", index=False)

print("Error report created.")