K&R 4-12 recursive converter int to string
No, this is not a correct solution.  Since i is static, the function will fail the second time it is used.

It also fails to handle INT_MIN correctly, since -INT_MIN will overflow an int.

You should never omit the "optional" braces for if, else, for, and while blocks.  By doing so, you are contributing to future coding accidents.  See this recent Apple security vulnerability and this quote from the author of jQuery:


  I really dis-liked having unnecessary braces. This… unfortunate… style preference plagued us for quite a while and caused all sorts of avoidable logic errors.