Is it unethical to post code in answers without citing sources?

Question

Sometimes, when answering SO questions, I am using in my answers the code which strictly speaking is not mine. I mean I have used this code in my applications, and often I have altered it more or less significantly, however I wasn't the author of the code, usually I found it somewhere on the Net.

So the question is: should I mention this fact in my answer? And, if I remember where the code came from, should I just refer the user to this site?

From one side I feel like giving an answer with code in place is much more helpful than just giving a link, however from another side I feel like "stealing" the credit.

EDIT: I am not speaking about the code taken from the open source projects or sites like CodeProject, where it is very clear where the credit goes, I am speaking about code snippets and solutions found on forums or sites like SO.

For example, OP asks how to add some functionality to his/her program, and there is a very specific API for doing so, does it matter that I came across this API on a site that is not Microsoft/Apple/Adobe etc. itself?

Answer 1

I'm not a lawyer either (so Bobby's disclaimer applies to my answer as well), but I'd say it depends on the complexity of the code sample.

If someone asks "How does a for loop work", and you find the following example on the web:

for(int i = 0; i < LIMIT; i++) {
    // do something
}

by all means, copy it verbatim. It's a textbook example, and it does not contain any significant creative value (I think the legal term is Threshold of Originality).

If the example is slightly more complex and could be considered to be an "original work" by itself, I'd either

• read it, understand it, and then write my own example, inspired by the other's work or
• copy it verbatim, providing a link and a reference to the original author (a Quotation) or
• copy it, modify it to better suit the question, and again provide a link and a reference to the original author (and mention that you modified it).

If the example is significantly complex (= a large piece of code), it's probably not suitable for inclusion in a SO answer anyway, so a link should suffice.

Answer 2

Disclaimer: I'm not a lawyer. So if I tell you nonsense, you get sued and send to Siberia, it's not my fault!

Everything you post on the Stack Exchange Network is licensed under the "Creative Commons 3.0 - Attribution - Share Alike". So you can not post stuff which would be incompatible with this license or you're not allowed to relicense it.

It all depends on the original license of this code. If it was provided as is in a Forum f.e., I'd assume a very liberal license which only requires attribution (including link) and allows usage for whatever, including quoting and usage on Stack Exchange with attribution.

Answer 3

In my opinion the real credit for the answer is to that site from which you are picking it, but if the answer too localize like pivot table in mysql, it is too local on various sites ,so there is no need to share link for it.So just give answer in cases like this .

But you have seen any new question whose answer is too unique and you find it on a link and found it rite and have good affert of that posted person then surely you need to provide the link.

Answer 4

I don't think there is any harm in giving credit where it is due. In some cases this could be difficult and in other cases the link could be out of date, but at least you've tried.