c++ push_back() a struct into a vector

Question

I have a large file with coordinates and the WayIds. Which I stored in a vector with the following struct:

struct SOne
{
    double y, x, wayId;
};

The file looks like this:

1. 52.8774, 6.7442, 777

2. 52.8550, 6.7449, 777

3. 52.8496, 6.7449, 776

In my program I have already filtered the WayIds with which I would like to continue working and stored in a vector named “way”. With a for loop i can find the coordinates but i don't know how to store them in a vector with struct.

    vector<SOne> MyWays;
for (int i = 0; i < Data.size(); i++)   { // Data -> my file with all coordinates and wayIds
    for (size_t j = 0; j < way.size(); j++){
        if (Data[i].WayId == way[j])  // way[j] -> here i get the WayId i like to work with
        {

        } // if
    } // for
} // for

I tried to follow this link: push_back() a struct into a vector but it didn't work for me. Can anyone give me a hint? Thanks in advance

Answer 1

1. Construct SOne .
2. Fill the object.

3. Insert into MyWays .

    SOne sOneObj; sOneObj.x = Data[i].X; sOneObj.y = Data[i].Y; sOneObj.wayId = Data[i].WayId; // = way[j] MyWays.push_back(sOneObj);

Answer 2

You can use std::vector::emplace_back to insert elements from your Data vector, assuming it has x,y, as well

struct SOne
{
    SOne( double y_in, double x_in, double wayId_in ):
     y(y_in), x(x_in), wayId(wayId_in)
     { }

    ~SOne() { }

     SOne& SOne=(const SOne& other) = default;
     SOne( const SOne& other ) =default;

    double y, x, wayId;
};

// Inside the if check simply do :
MyWays.emplace_back( Data[i].X, Data[i].Y, Data[i].WayId ) ;

Answer 3

Your struct should already have a default copy constructor to do the job so you can just use MyWays.push_back(SOne(Data[i])); with no changes to other parts of your code

Answer 4

A bit late to the party, but I'd probably insert the data like this:

MyWays.push_back({Data[i].X, Data[i].Y, Data[i].WayId});

This should invoke the move variant of push_back(), which cuts down on copying. Also, I'd probably use an integer for WayId, but that's more a matter of preference.