Can I insert values into vector of pointers using insert function?

Question

Suppose Foo is any class.

Foo f[5];

std::vector<Foo*> v;

I can insert the elements into vector of pointers using a for loop statement:

for (size_t i = 0; i < 5; i++)
    v.push_back(&f[i]);

Is it possible to insert them using std::vector::insert() function and why not? I have tried several times it failed something like this:

v.insert(v.end(), &f[0], &f[5]); // error

Answer 1

If you mean, with a single call to insert , then no - that can copy a range, performing type conversions if needed, but can't apply arbitrary transformations like taking the address of each element.

You could use std::transform :

std::transform(std::begin(f), std::end(f),
               std::back_inserter(v),
               [](Foo & f) {return &f;});

although that's probably less clear than a simple loop, especially if you use new-style syntax

for (Foo & foo : f) {
    v.push_back(&foo);
}

Answer 2

Yes you can use insert also. But there are few differences between these two operations:-

push_back puts a new element at the end of the vector and insert allows you to select position. This impacts the performance. insert forces to move all elements after the selected position of a new element. You simply have to make a place for it. This is why insert might often be less efficient than push_back.