Find weak_ptr in vector

I am trying to find weak_ptr in vector. I am using lambda expression as a third parameter to find but I can't understand why this code is not compiled:

std::vector<std::weak_ptr<Car>> cars;

std::shared_ptr<Car> lambo = std::make_shared<Car>();
std::weak_ptr<Car> wPtr(lambo);
cars.emplace_back(lambo);

const auto pos = std::find(cars.begin(), cars.end(), [&wPtr](const std::weak_ptr<Car>& ptr1) {
    return ptr1.lock() == wPtr.lock();
});

if (pos != cars.end())
    cout << "Not found!" << endl;

Maybe someone could point me what I am doing wrong. Thanks in advance.

Solution

I'm sure you meant std::find_if (which takes a predicate), not std::find (which takes a value).

Also fixing your conditional at the end, and adding appropriate boilerplate, we get:

#include <vector>
#include <memory>
#include <iostream>
#include <algorithm>

struct Car {};

int main()
{
    std::vector<std::weak_ptr<Car>> cars;

    std::shared_ptr<Car> lambo = std::make_shared<Car>();
    std::weak_ptr<Car> wPtr(lambo);
    cars.emplace_back(lambo);

    const auto pos = std::find_if(cars.begin(), cars.end(), [&wPtr](const std::weak_ptr<Car>& ptr1) {
        return ptr1.lock() == wPtr.lock();
    });

    if (pos == cars.end())
        std::cout << "Not found!" << std::endl;
    else
        std::cout << "Found!" << std::endl;
}

// Output: Found!

Find weak_ptr in vector

(live demo)