error handling

src/basic/error_handling.py

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+# Error Handling
+
+# Basic try / except
+
+try:
+    number = int('anikuttan')  # invalid conversion
+except:
+    print("Something went worng")
+
+
+try:
+    x = int("abc")   # invalid conversion
+except ValueError:
+    print("Oops! That was not a number.")
+
+
+# Handling Multiple Exceptions
+try:
+    result = 10 / 0
+except ZeroDivisionError:
+    print("You cannot divide by zero!")
+except ValueError:
+    print("Invalid value!")
+
+# Catching All Exceptions
+try:
+    print(10/0)
+except Exception as e:
+    print(f"error {e}")
+
+
+# else with try
+# The else block runs only if no exception occurs.
+try:
+    x = int("10")
+    # x = int("abs")
+except ValueError:
+    print("Invalid number")
+else:
+    print("Conversion successful:", x)
+
+
+# finally Block
+# The finally block always runs
+try:
+    x = int("as")
+except ValueError:
+    print("invalid conversion")
+finally:
+    print("Finally called")
+
+
+# Raising Exceptions
+
+def withdraw(balance, amount):
+    if amount > balance:
+        raise ValueError("Insufficient funds!")
+    else:
+        return balance - amount
+
+
+try:
+    withdraw(100, 200)
+except ValueError as e:
+    print("Error:", e)
+
+
+# Custom Exceptions
+
+class NegativeNumberError(Exception):
+    pass
+
+
+def square_root(x):
+    if x < 0:
+        raise NegativeNumberError(
+            "Cannot take square root of negative number!")
+    return x ** 0.5
+
+
+try:
+    print(square_root(-9))
+except NegativeNumberError as e:
+    print("Custom Error:", e)
+
+
+# Summary
+
+# try / except → catch errors
+
+# else → run if no error
+
+# finally → always runs
+
+# raise → trigger your own error
+
+# Custom exceptions → more control in big apps