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Python Try...Except

The try block lets you test a block of code for errors, while the except block lets you handle the error. Below is a list of common exceptions in Python, and clicking on each will scroll you to the explanation and examples.

Common Python Exceptions

  • ZeroDivisionError: Raised when division or modulo by zero occurs.
  • TypeError: Raised when an operation is applied to an object of an inappropriate type.
  • ValueError: Raised when a built-in operation or function receives an argument with the right type but inappropriate value.
  • IndexError: Raised when a sequence subscript is out of range.
  • KeyError: Raised when a dictionary key is not found in the dictionary.
  • FileNotFoundError: Raised when trying to open a file that does not exist.
  • AttributeError: Raised when an invalid attribute reference or assignment is made.
  • ImportError: Raised when an import statement fails.
  • OSError: Raised for system-related errors like file operations.
  • RuntimeError: Raised when an error is detected that doesn't fall into any of the other categories.

ZeroDivisionError

This error occurs when a number is divided by zero. For example:

# ZeroDivisionError example
try:
    result = 5 / 0
except ZeroDivisionError:
    print("Error: You cannot divide by zero!")

Output

Error: You cannot divide by zero!

TypeError

This error occurs when an operation is applied to an object of an inappropriate type. For example:

# TypeError example
try:
    result = '5' + 5
except TypeError:
    print("Error: You cannot add a string and an integer!")

Output

Error: You cannot add a string and an integer!

ValueError

This error occurs when a built-in operation or function receives an argument with the right type but inappropriate value. For example:

# ValueError example
try:
    num = int("abc")
except ValueError:
    print("Error: Invalid literal for int()!")

Output

Error: Invalid literal for int()!

IndexError

This error occurs when trying to access an index that is out of range in a list. For example:

# IndexError example
try:
    items = [1, 2, 3]
    print(items[5])
except IndexError:
    print("Error: Index is out of range!")

Output

Error: Index is out of range!

KeyError

This error occurs when trying to access a key in a dictionary that does not exist. For example:

# KeyError example
try:
    my_dict = {"name": "Karthick"}
    print(my_dict["age"])
except KeyError:
    print("Error: Key 'age' not found in dictionary!")

Output

Error: Key 'age' not found in dictionary!

FileNotFoundError

This error occurs when trying to open a file that does not exist. For example:

# FileNotFoundError example
try:
    f = open("non_existent_file.txt")
except FileNotFoundError:
    print("Error: File not found!")

Output

Error: File not found!

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