Helpful comments for existing code

Prompt for helpful comments and function descriptions in existing code, without changing logic or names. Paste it into an AI tool of your choice, which then comments the code.

Topic: Understanding code
Type: Prompt
Level: Beginner
Time: about 5 min

Results depend on the tool, the model and what you enter.

Result preview

Example: written by our editors, not real AI output.

def net_price(gross, rate): """Converts a gross price into the net price. gross: price including tax, as a decimal. rate: tax rate as a fraction, e.g. 0.2. Returns the net price rounded to two places. """ # Round only at the end so rounding errors do not add up. return round(gross / (1 + rate), 2) Check: what happens when rate = -1?

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LanguageWhich language is the code in?

ReaderWho will read the code later?

CodePaste the code – no keys or customer data

Your prompt

Write helpful comments and function descriptions for the following code.
Language: [Language]
Who will read the code later: [Reader]
Code:
<code>
[Code]
</code>
Rules: 1. For each function, describe in one to three sentences what it does, which inputs it expects and what it returns. 2. In the code, only comment places where the why is not obvious. 3. Do not repeat what the code already says. 4. Mark assumptions and edge cases you notice with "Check:". 5. Do not change any logic or names. Use the usual comment style of the language. Return the commented code and, below it, a list of the Check points.

Take particular care to explain the why instead of retelling the code and change neither logic nor names.

Before you answer, check: Are all instructions met? If key information is missing or a placeholder in square brackets is still in the text, ask instead of guessing. Mark assumptions as assumptions.

This is an instruction for an AI, not the result itself.

Where this prompt works

These AI tools are a good fit for this prompt:

How to use it

Fill in the fields or tap a suggestion. Leave out names, addresses and other personal data.
Copy the finished prompt into an AI tool of your choice.
Read through the comments and resolve the Check points before you adopt them.

Why does this work?

Comments that explain the why stay useful after changes. The rule not to change logic keeps the change small and easy to review.

Tips

Leave out sensitive values such as keys or passwords before pasting, or replace them with placeholders.

You may use our prompts freely, including at work. Please do not republish them as your own collection. We give no warranty for AI results; check them yourself. Terms of use

Helpful comments for existing code

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