implicit declaration of function itoa is invalid in c99

Question

When I try use the function itoa(), I get the warning:

implicit declaration of function is invalid in c99.

I have

Answer 1

The problem is that itoa() isn't a standard function.

You should take a look at this link which gives you some alternative implementations

Answer 2

An alternative that is commonly used in place of itoa is sprintf/snprintf. These are part of stdio.h.