我如何比较将std :: vectors的内容与自定义对象进行比较

Question

I have 2 vectors which contain custom objects which I am using in a unit test. I cannot change the implemetation of the objects contained in the vectors, and the objects do not contain an == overload.

I would like to compare every object in these vectors to determine if they have the same value in one of the member variables at the end of my unit test.

Currently I am sorting the vectors and then looping over the contents like this:

// Sort predicate
bool SortHelper(MyObject& w1, const MyObject& w2)
{
    return (w1.MyInt() < w2.MyInt());
};

... 

//Ensure the sent and received vecs are the same length
ASSERT_EQ(vectorOne.size(), vectorTwo.size());

// Sort the vectors
std::sort(std::begin(vectorOne), std::end(vectorOne), SortHelper);
std::sort(std::begin(vectorTwo), std::end(vectorTwo), SortHelper);

// Ensure that for each value in vectorOne there is a value for vector2
auto v1Start = std::begin(vectorOne);
auto v1End = std::end(vectorOne);
auto v2Start = std::begin(vectorTwo);
auto v2End = std::end(vectorTwo);

if ((v1Start != v1End) && (v2Start != v2End))
{

    while (v1Start != v1End) {
        EXPECT_TRUE(v1Start->MyInt() == v2Start->MyInt());
        ++v1Start;
        ++v2Start;
    }
}

I have also attempted some combinations of std::find_if to achieve this goal but I failed to find a solution.

I know that in C# that I could compare the contents like this:

foreach (MyObject m in listOne)
{
    Assert.IsTrue(listTwo.Any(i => m.MyInt == i.MyInt));
}

Can someone show me a better/more concise way for me to compare the contents of my vectors. I would like to use STL and/or Boost wherever possible

Answer 1

You can use std::equal with an appropriate predicate:

bool ok = equal(begin(vectorOne), end(vectorOne),
                begin(vectorTwo), end(vectorTwo),
                [](const MyObject& w1, const MyObject& w2)
                { return w1.MyInt() == w2.MyInt(); });

The above overload isn't available before C++14, so you'd need to call this one, after checking that the length of the vectors is the same:

bool ok = equal(begin(vectorOne), end(vectorOne),
                begin(vectorTwo),
                [](const MyObject& w1, const MyObject& w2)
                { return w1.MyInt() == w2.MyInt(); });