"Hello" is actually 6 characters (including the \0), so you'll still get undefined behavior if you try to print your array with it.
Remember that each string needs the amount of characters you need to store + 1 for the \0 char.
Originally Posted by Adak
io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
Originally Posted by Salem
You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.
Outside of your DOS world, your header file is meaningless.