I know that unique_ptr makes the smart pointer own the resource and thus it doesn’t allow multiple pointers to point to the same resource.

But why then is it allowed to create a raw pointer of that smart pointer with .get() and then pass it to a function?
At the end you have two pointers that have ownership of the resource and with the ability to change its value? Which would violate the rule of unique_ptr smart ptr exclusively owning the resource.

In the example below I made a simple program that changes the value that the smrt pointer smrtPtr is pointing at.

Ex:

#include <iostream>
#include <memory>
#include <utility> //move semantics

void changeValue(int* ptr)
{
    if (!ptr)       //check if pointer is null
        return;
    *ptr = 17;       //change value to 17
}



int main()
{

    auto smrtPtr{ std::make_unique<int>(5) };
 
    changeValue(smrtPtr.get());    //creates a raw pointer of smrtPtr

    if (smrtPtr)            //if it does contain resource
        std::cout << *smrtPtr;

        return 0;
}

Thanks a lot