P.S.:this is not a test.i am just not at all able to understand why perl behaves this way.

If you iterate over an array @array with foreach, perl doesn't build a list to iterate over, as it does for other cases, i.e. the iterator of the foreach loop goes on until it hits the boundary of the array. If the array changes under the hood, well, more rope then. Consider:

foreach (@array, 1) {
    #push @array,'a';#replace following statement with this one
    @array = (@array,'a');
    print;
}
__END__
a
1
[download]

Since in the above example there's more to the foreach loop than an array, perl builds a temporary list of all elements to foreach, aliasing them, and further changes to the array go by unnoticed. If you have just an array to iterate over, that overhead (of list building) is not done, but array boundaries aren't remembered either. Both behaviours are sensible, since if you have a composed list, there has to be something else to iterate over - hence the temporary list. If you iterate over an array alone, there's no need to build a list.

BTW, the two statements

push @array,'a';
@array = (@array,'a');
[download]

do have the same effect with regards to the array iterator in foreach, but the latter is less perlish and produces more overhead, since it copies over the contents of the array every time (the pointer to the array stays the same).

That said, what are you trying to do? An infinite loop is built much easier like so:

1 while 1
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_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}