Does the last element in a loop deserve a separate treatment?

Question

When reviewing, I sometimes encounter this kind of loop:

i = begin
while ( i != end ) {    
   // ... do stuff
   if ( i == end-1 (the one-but-last element)          


        

Answer 1

I know I've seen this when people tried to join elements of an array into a comma-seperated string:

for(i=0;i0) {
     string += ','
   }
   string += elements[i]
}

You either have that if clause in there, or you have to duplicate the string += line again at the end.

The obvious solution in this case is

string = elements.join(',')

But the join method does the same loop internally. And there isn't always a method to do what you want.