C++ STL algorithms: get pointers of elements in container

Question

I have a function that is taking two pointers as parameters.

bool function(T* a, T* b);

And a container (vector).

vector<T> vector;

I wish to use an algorithm of the STL (the for_each) to apply the function on the elements of the vector. However, I don't know if the pointers of the elements will go automatically in the function as parameters. For example, will

for_each(vector.begin(), vector.end(), function(/*something here?*/))

work, or I need to go with a loop (the new for each in loop of the C++11) ?

Answer 1

You cannot use std::for_each() with your function for at least two reasons:

• std::for_each passes a single parameter to the lamba, your function () takes two parameters.

• std::for_each passes a reference to each member of the container, and not a pointer.

Answer 2

Try utilizing a normal for loop for solving this problem.

vector<T> v;
for(size_t i(0); i < v.size()-1; ++i)
{
    function(&v[i], &v[i+1]);
}

This will pass as the values an address to elements i and i+1 of v which of type T.