strcpy - Copies the content pointed by src to dest stopping after the terminating null-character is copied.
dest should have enough memory space allocated to contain src string.

strncpy - Copies the first num characters of src to dest.
No null-character is implicitly appended to dest after copying process. So dest may not be null-terminated if no null-caracters are copied from src.
If num is greater than the length of src, dest is padded with zeros until num.

Now, maybe I just dont know, but why would you use strcpy when strncpy is available? I guess I really havent found a solid answer. I mean what were they thinking with strcpy? Were they just trying to create an easy way to have buffer overflows all over? (Same goes for strcat and strncat). I guess I am glad now to use C# and VB.net the majority of the time when you really don’t have to worry about this stuff. With C/C++ its all over the place, and you can tell, just look at all the buffer overflow vulnerabilites withing Microsoft products.