Edit: I\'ve added the source for the example.
I came across this example:
char source[MAX] = \"123456789\";
char source1[MAX] = \"12
strncpy combats buffer overflow by requiring you to put a length in it. strcpy depends on a trailing \0, which may not always occur.
Secondly, why you chose to only copy 5 characters on 7 character string is beyond me, but it's producing expected behavior. It's only copying over the first n characters, where n is the third argument.
The n functions are all used as defensive coding against buffer overflows. Please use them in lieu of older functions, such as strcpy.