#the following gives: a 1 b 2 c 3

@arr1 = qw(a b c);
@arr2 = qw(1 2 3);

while (@arr1) {push @arr3, shift @arr1,shift @arr2}

print "@arr3";



#BUT why does the following give an infinite loop?


@arr1 = qw(a b c);
@arr2 = qw(1 2 3);

while ($push @arr3, shift @arr1,shift @arr2){}