5 Common Python Errors and How To Avoid Them

Introduction:

In this tutorial, we will learn five common errors in Python programming and strategies to prevent them. Python is widely valued for its straightforwardness and ease of use. It is susceptible to errors like any programming language. Understanding how to recognize and resolve these issues is essential for efficient debugging, time-saving, and preventing future coding challenges. This tutorial will outline common Python errors and effective troubleshooting techniques.

1. Syntax Error:

SyntaxError occurs when the Python interpreter analyzes your code and finds errors that do not follow the syntax rules. Some causes of syntax errors are:

1. Unclosed the strings
2. Misspelling the keywords in Python
3. Missing some open or closing brackets, parentheses, or braces
4. Issues of indentation
5. The assignment operator (=) misusing
6. Use the new Python syntax on older versions of Python.

When the syntax error occurs, then a traceback is created to help you identify the problem. We give an example below -

Output:

Now, we run the above code. The syntax in line 1 is invalid because the first character of the dictionary is missing a colon (:) that separates the character "Jack" with the value 20. The result is given below -

 
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 1
    s = {"Jack" 20,
         ^^^^^^^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?   

The traceback message contains multiple carets (^) to indicate where the incorrect syntax was encountered. Sometimes, it cannot pinpoint the exact location, but it often gives clues as to where the problem is. To resolve this issue, consider the following information as you recover:

1. Document name
2. Line number
3. A location which is indicated by the caret (^)
4. Error messages can help you understand the nature of the problem.
5. Including additional questions at the end of the error message provides important information.

So, the correct code is -

Output:

Now, we run the above code. The output is given below -

 
Jack is 20 years old boy
Jil is 18 years old boy   

Here, we are learning some tips for avoiding syntax errors in Python:

1. Before executing your code, thoroughly review it for any typos or error.
2. Utilize a code editor featuring syntax highlighting to detect syntax errors easily.
3. Thoroughly examine the error message to pinpoint the exact location of the error.

2. Indentation Error:

IndentationError occurs in Python when there is an indentation issue in the code. Typical causes include mixing tabs and spaces, improper spacing, incorrectly nested blocks, or spaces at the start of a statement.

When the Indentation Error occurs, then a traceback is created to help you identify the problem. We give an example below -

Output:

Now we run the above code and an error message comes in the output. The output is provided below -

 
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 2
    print("The indentation is incorrect")
    ^^^^^
IndentationError: expected an indented block after 'if' statement on line 1

To work around and avoid this issue, use an editor or IDE configured to a code formatter like Black to format your code as you type. The Pylance linter may help you identify the error. So, the correct code is -

Output:

Now, we run the above code. The output is given below -

Here, we are learning some tips for avoiding indentation errors in Python:

1. Indent each level with four spaces.
2. Avoid mixing tabs and spaces.
3. Ensure consistent indentation throughout your code.

We can use a code editor with automatic indentation features for avoid indentation errors. The examples of code editor are PyCharm or Visual Studio Code.

3. Name Error:

In Python, a NameError occurs if you use an identifier. It has not been defined or is out of scope. This error can also happen if you reference a variable before assigning it or if you misspell an identifier. We give an example below -

Output:

Now we run the above code and an error message comes in the output. In this example, the age variable is not defined but is used. As a result, Python throws an exception. The output is as follows -

 
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 1, in <module>
NameError: name 'age' is not defined   

We solve this problem by ensuring that the variable or function name is used. Check for typos. Also make sure the variable you want to use is in the input. Setting up a linter in your editor will help you catch these issues early in the development process. So, the correct code is -

Output:

Now, we run the above code. The output is given below -

 
30   

Here are some tips for avoiding name errors in Python:

1. Remember that all variables and functions are declared before they are used in the code.
2. Verify the spelling. Capitalization of your variable and function names.
3. Utilize Python's built-in debugging tools, like print statements. These can help you identify and resolve name errors.

4. Value Error:

The "ValueError" exception occurs when a function receives a parameter of the correct type but the wrong value. For instance, the int()function expects an integer string such as "33"; providing a string like "thirty-three" will result in a ValueError. We give an example below -

Output:

Now we run the above code and an error message comes in the output. The output is given as follows -

 
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 'thirty-three'   

Another common cause is passing an empty iterable to the `max()` or `min()` functions. An example of this is max([]). To fix this, ensure you provide the correct data type and value to these functions. Consult the documentation for the specific function to ensure your input matches the expected format. When appropriate, use try-except blocks to handle potential user input errors gracefully and avoid ValueErrors that could crash your program. So, the correct code is -

Output:

Now, we run the above code. The output is given as follows -

 
33   

Here are some tips for avoiding value errors in Python:

1. Validate user inputs.
2. Using the try-except blocks.
3. Check for empty iterables.
4. Consult the function documentation.
5. Using the conditional checks.
6. Test with diverse inputs.
7. Careful for type conversion.
8. Utilize the debugging tools.

5. Type Error:

TypeError exception in Python means you are dealing with an invalid or qualified object data type. For example, try splitting a string by a number. We give an example below -

Output:

Now we run the above code and an error message comes in the output. The output is given as follows -

 
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 1, in <module>
TypeError: unsupported operand type(s) for /: 'str' and 'int'   

This exception may occur when trying to evaluate parameters such as floating-point numbers or integers. It can also happen when the wrong type is used for a function. For example, passing code to the len() function that expects an extension can cause a type error. Additionally, calling a function with too few arguments or comparing different data can cause a type error. So, the correct code is -

Output:

Now, we run the above code. The output is given below -

 
Hello CodersHello CodersHello CodersHello CodersHello Coders   

Here are some tips for avoiding Type errors in Python:

1. Ensure inputs are of the correct type before processing.
2. Use functions like isinstance() to check data types.
3. Review function documentation for expected argument types.
4. Convert data to the appropriate type as needed.
5. Test your code with different input types to catch potential errors.
6. Employ type annotations to make expected types clear.
7. Use linting tools to catch type issues before runtime.

Conclusion:

This tutorial teaches us about 5 common Python errors and how to avoid them. Python is a versatile language with many features. However, like any language, it may encounter errors. This tutorial covers some of the most common errors in Python and their solutions. By learning about these errors and how to resolve them, you can become a more skilled and confident Python programmer.