I Confused print and return for Months. Here’s What Finally Clicked

#python#coding#softwaredevelopment#programming

The simple Python mental model that turned my “silent” functions into powerful tools.

There are moments in programming where you feel like the computer is gaslighting you. For me, one of the first was writing a Python function that looked perfect—no errors, no warnings—but somehow “did nothing.”

I’d run my code, stare at the screen, and mutter: “Why won’t you just work?”

Spoiler: the bug wasn’t Python. The bug was me. I didn’t understand the difference between print and return.

And if you’re new to Python, you’ve probably fallen into the same trap.

My First "Silent" Function

My first attempt at a function to add two numbers looked like this:

def add(x, y):
    print(x + y)

It seemed to work perfectly. When I called add(2, 3), the number 5 appeared on the screen. Success!, I thought.

But the moment I tried to do something else with that number, my code blew up.

result = add(2, 3)
print(result + 10)

Python slapped me with a TypeError. Apparently, I was trying to add 10 to... None. I sat there thinking: “None? What None? I saw the 5 on the screen. Where did it go?”

The truth is, print was playing a trick on me. It lit up the screen for me, the human, but left my function empty-handed.

print Is for You, return Is for the Program

The fix was painfully simple. I needed to return the value instead of printing it.

def add(x, y):
    return x + y

Now, the function gives back a real value, so my program could use it.

result = add(2, 3)
print(result + 10)  # Output: 15

This was the day I realized: print is for me, the human. return is for the program.

Think of it this way:

• print is a monologue. It speaks directly to the user (you).
• return is a dialogue. It speaks to other parts of your code.

The Debugging "Flashlight"

I still use print—a lot. It’s the cheapest flashlight you’ve got for debugging. When a variable’s value is a mystery, I’ll sprinkle print statements to peek inside.

def calculate_total(prices):
    total = sum(prices)
    print("DEBUG:", total) # My flashlight
    return total

This is a great use of print. The trick is knowing when to stop. Debugging with print is fine. Building logic around print is where the wheels fall off. It’s a flashlight, not an electrical outlet.

Final Takeaway

Mastering the difference between print and return is a turning point. It's when you stop writing functions that only talk to you and start writing functions that can be composed, reused, and scaled. That’s when Python stops being a toy and starts being a tool.

So next time your function “does nothing,” remember: it might not be Python that’s broken. It might just be you, staring at a flashlight where you should have had a dialogue.

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Aaron Rose is a software engineer and technology writer at tech-reader.blog and the author of Think Like a Genius.