Creating a Unique Character List with ASCII Values in Python

Learn how to write a Python function that generates a list of unique characters concatenated with their `ASCII` values, while avoiding common pitfalls with variable names.
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Understanding the Problem: Unique Characters with ASCII Values

When working with strings in Python, you might encounter a situation where you need to extract unique characters and display them along with their corresponding ASCII values. This type of task is not only a useful programming exercise, but it also helps strengthen your understanding of data structures and character encoding.

For example, given the input string "pythonbook", your goal is to create a list that includes each unique character prefixed and suffixed with its ASCII value. The output, in this case, should look like this:

[[See Video to Reveal this Text or Code Snippet]]

The Error: Using Reserved Keywords

While attempting to write a function for this purpose, you might run into problems if you're not careful with variable naming. In Python, using str — which is a built-in keyword — as a variable name can lead to errors because it conflicts with Python's built-in string handling functionalities.

Here's what the problematic version of the function may look like:

[[See Video to Reveal this Text or Code Snippet]]

If you run this code, you'll likely encounter an error due to your use of str as a variable name.

The Solution: Correct Naming and Implementation

To fix this issue, it is vital to choose a different name for your input variable. Here’s a refined version of the function:

[[See Video to Reveal this Text or Code Snippet]]

Breaking Down the Solution

Function Definition:

We define a function function_name that takes a parameter s.

List Initialization:

We initialize an empty list lis to store our results.

Loop Through Characters:

We loop through the string by its index using range(len(s)).

Checking Uniqueness:

Inside the loop, we check if the character s[i] is already in the list lis. If not, we proceed to create the desired format.

Construct the String:

We use ord(s[i]) to get the ASCII value of the character and concatenate it with the character itself in the appropriate way.

Return the Result:

Finally, we return the list containing both the unique characters and their ASCII representations.

Output

Running the corrected function with the input "pythonbook" will give you:

[[See Video to Reveal this Text or Code Snippet]]

Final Thoughts

This exercise is a great reminder of the importance of choosing meaningful variable names that do not conflict with Python's built-in keywords. Remember, it is crucial not to mix up your variable names with reserved keywords to prevent errors and misunderstandings in your code.

In the world of programming, small mistakes can lead to significant headaches, so attention to detail is essential. Happy coding!