Key Highlights

 

• Find out what the Python upper() function does, and just how useful it can be.
• Learn how you can uppercase text even if you want to avoid using built-in Python methods.
• It’s filled with real examples and some funny stories from my days of learning to code.
• It’s written in a way that’s simple for beginners to understand and still provides technical information for more advanced programmers.
• It’s perfect for people learning the basics of Python or understanding ASCII & Unicode.
• It even contains 7 practical techniques and one of my favorite Unicode tricks.
• It contains internal and external links to enrich your understanding of the topic.

If You’re Searching for “How Do I Uppercase a Python String Without Using Built-ins…” You’re in the Right Place 👍

If you’ve been searching for how to uppercase strings in Python, it’s likely for one of two reasons:

They wish to know how Python course really works at the scene-media–and particularly how to get letters into upper case without using upper.

So here now though I will tell you the answer:

👉 Uppercasing any Python string can be done through the Python built-in method of upper, OR can be done by you using lists, Unicode, ASCII or even custom functions.

But that’s the boring version. I can show you the step-by-step procedure like I were instructing a friend- because believe me I had the same issue as well in my early years of programming.

Understanding What the Python upper() Function does (and why it is important).

When I learned Python Beginners first, I believed that such things as Python string Format were magic.

I typed:

print("hello".upper())

And boom — HELLO. It felt like cheating. 😂

But this is what is really going on:

python upper scans character by character.

It verifies that it is a lowercase letter.

In case yes it goes to the uppercase version using Unicode.

If no, it leaves it alone

It’s simple. It’s elegant. It works every time.

However, what should you do for learning, but you want to do uppercase without the help of built-in Python method?

That’s where the fun begins.

⭐ 1. Python upper (Just to Set the Stage)

I understand that the entire purpose of this article is to be educated on uppercase without inbuilt method used in Python. But we should first know the rule before we break it.

name = "python explorer"
print(name.upper())

Output:

PYTHON EXPLORER

Python upper is quick, consistent and easy to learn. However, we will not have to follow the path of the golden milk, we should learn how to create this characteristic ourselves.

⭐ 2. All-Letter: List of Letters (My First DIY Method 😅)

This is literally the first trick that I employed when I was not sure how Unicode operated.

I built two lists:

• One for lowercase letters
• One for uppercase letters

Like this:

lowercase = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
uppercase = ['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']

And I would map every lower case to its uppercase counterpart.

for char in word:
    if char in lowercase:
        index = lowercase.index(char)
        result += uppercase[index]
    else:
        result += char

The first time that I did so, this seemed like a magic that I was making myself. ✨

It was slow, ay, but marvellous gratifying.

⭐ 3. Write It to Uppercase without Built-ins in ASCII This Is Where I Felt like a Real Programmer 🤓

Here’s the cool part:

• ‘a’ → ASCII 97
• ‘z’ → ASCII 122
• ‘A’ → ASCII 65
• ‘Z’ → ASCII 90

The difference is 32.

To convert lowercase to uppercase, no built-ins:

uppercase_code = ord(char) - 32
uppercase_letter = chr(uppercase_code)

Example:

word = "python"
result = ""

for char in word:
    if 97 <= ord(char) <= 122:
        result += chr(ord(char) - 32)
    else:
        result += char

That’s it.

You have now learned a bit about Python upper on a behind-the-scenes level.

⭐ 4. Encoding in Unicode (Not ASCII)

ASCII is limited to English letters only.

Unicode covers:

• French
• Chinese
• Hindi
• Emojis (yes, emojis 😄)

The fact that Python upper actually uses Unicode internally upgraded my brain.

To capitalize without inbuilt python technique by use of Unicode:

if 'a' <= char <= 'z':
    result += chr(ord(char) - 32)

Unicode is similar to ASCII in terms of spacing in English letters.

⭐ 5. With a Dictionary Mapping (Readable and Friendly to Beginners).

At some point, I realized:

What, say, I make a dictionary to every letter? It might look cleaner.”

Example:

mapping = {chr(i): chr(i - 32) for i in range(97, 123)}

Then:

if char in mapping:
    result += mapping[char]

I have applied this method in one of my school projects. It’s great for clarity.

⭐ 6. Custom Function which is an imitation of Python upper()

At this stage, I would desire my own role to be official.

So I wrote:

def my_upper(word):
    result = ""
    for char in word:
        if 'a' <= char <= 'z':
            result += chr(ord(char) - 32)
        else:
            result += char
    return result

This is the nearest Python alternative of DIY upper.

⭐ 7. The List Comprehension (For Those Who Love Clean, Short Code) is used.

The fancy version that is readable is this one:

result = ''.join(chr(ord(c)-32) if 'a' <= c <= 'z' else c for c in word)

I would not suggest this to novices, but otherwise, it is beautiful in Python.

My Honey-True Opinions (and a Little Tale).

My initial attempt at doing uppercase without built-in Python method was a total failure as I did not have the slightest idea of how characters worked.

I believed that Python was keeping the capital letters in some table somewhere.

In theory, that was not completely wrong… however, learning about Unicode, ASCII, and indexing made me have a different perception of programming.

Assuming you are learning this now, then I tell you that you are doing what many novice programmers never even think of doing. Knowing this will enable you to help you in:

cryptography encoding / decoding text processing building compilers handling multilingual data

Yes this is not an arbitrary coding trick.

You are developing actual computer-science-level knowledge. 🚀

 

Final Thoughts

Whatever you extract out of this article, do it in this:

✔ Python upper() is simple

But the reasoning of it is interesting.

✔ The best way to learn how text interacts within computers is to do uppercase with no in-built Python method.

These methods will certainly be beneficial, whether you have to create your beginner scripts or prepare for the interviews.

And by the way, ever come up with your own version of upper? You are more or less writing mini-python. 🔥

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