Suppose a class Object exists.
I now have vector<Object> vec
If I now do in some part of my code:
for(auto p : vec){
//something with p
}
Does this make a new object p for every object that actually in the iterator? Or does it actually just go through the actual objects in the list? I'm asking because I've also seen auto& p
Yes, it will make a copy of each item, to have a reference you should do:
for (auto& p : vec) {}
Also, if you want to protect items from any change, you can have const to reference:
for (const auto& p : vec) {}
The range based for loop you have
for(auto p : vec) /* ... */
copies every element in vec into the loop variable p. Hence, any changes you apply to p does not affect the elements in vec. And yes, if you change the loop to
for (auto& p : vec) /* ... */
then p is a reference to the vec elements, and changes applied to p are changes you apply to the corresponding vec element.
