Program won't crash when it should

(GCC C)
I ran a pointer over each member of an integer array, storing one character of input in each cell.

The program seems to consistently crash when I try to store X+3 or more characters, where X is the size of the array, but if I do not exceed X+2 it will not crash.

Why does it crashes exactly at the point it does, but not for X+1 or X+2?

Well from the standard:
The printf function is equivalent to fprintf with the argument stdout interposed before the arguments to printf.

The fprintf function returns when the end of the format string is encountered.

So the program terminates after printf returns and stdout is flushed and closed.