Why is strdup considered to be evil

Question

I\'ve seen some posters stating that strdup is evil. Is there a consensus on this? I\'ve used it without any guilty feelings and can see no reason why it is wo

Answer 1

Many people obviously don't, but I personally find strdup evil for several reasons,

• the main one being it hides the allocation. The other str* functions and most other standard functions require no free afterwards, so strdup looks innocuous enough and you can forget to clean up after it. dmckee suggested to just add it to your mental list of functions that need cleaning up after, but why? I don't see a big advantage over reducing two medium-length lines to one short one.

• It allocates memory on the heap always, and with C99's (is it 99?) VLAs, you have yet another reason to just use strcpy (you don't even need malloc). You can't always do this, but when you can, you should.

• It's not part of the ISO standard (but it is part of the POSIX standard, thanks Wiz), but that's really a small point as R.. mentioned that it can be added easily. If you write portable programs, I'm not sure how you'd tell if it was already defined or not though...

These are of course a few of my own reasons, no one else's. To answer your question, there is no consensus that I'm aware of.

If you're writing programs just for yourself and you find strdup no problem, then there's much less reason not to use it than if you are writing a program to be read by many people of many skill levels and ages.