iterators vs []

Performance wise, when you loop through all element of a list/vector using indexing, every iteration of the loop starts a element 0 and goes to i, while if you use iterators you only do a +1 operation every iteration. Depending on the size of the list/vector and implementation of the indexing operator, this can really make a diffrence.

+ there are other advantages: read http://en.wikipedia.org/wiki/Iterator#Contrasting_with_indexing

thx for the posts. So the only difference is the way that these two thing perform the same operation? I guess I will try to only use iterators now, thx

For these, there's no general way to know whether using an iterator or using operator[] is more efficient. It depends on the implementation, the CPU instruction set available and the optimizations done by the compiler.Even though you are right that it is impossible to make a general statement about performance that holds true under all conditions, I would still consider it safe to assume that iterators are at least as efficient as operator[] when iterating through an STL container. I just find it hard to imagine, why any implementation would make iterators deliberately perform worse. If there is no performance gain possible, iterators can just be implemented as an integer i where dereferencing then calls operator[].