What does the expression for(int& item : v4) means :

Question

v4 is a vector, the loop is to iterate through the vector list and display the elements in the vector. what does the expression inside the for loop means.
the code is as follows:

Answer 1

This is a range-based for loop . It iterates over all the elements of the v4 vector, and lets you process via the item variable in each iteration.

Answer 2

It iterates through the container v4, whatever that is, let's say it's a vector The & in "int&" means that it's a reference, if you change the item, it's gonna change the value in the as well. Similar to

for (int i = 0; i < v4.size(); i++){
        item = v4[i];
        //...
    }