不能将struct类型的元素添加到vector吗？

Question

I'm trying to add two values into a vector of a custom type, without creating a variable of that type.

typedef struct duo{
    int uniqueID; 
    double data; 
};

vector<duo> myVector;
myVector.push_back({1,1.0});

But it won't allow it??

The only way I can get it to work is if I create the variable, but feels tedious...

vector<duo> myVector;
duo temp = {1,1.0};
myVector.push_back(temp);

Also... why can't I do this?

duo temp;
temp = {1,1.0}; 

but I can do this:

duo temp = {1,1.0};

???

Answer 1

You can avoid creating the temporary object while building your vector using std::vector::emplace_back() .

Below is the code sample.

class duo {
public:
    duo(int uniqueID_, double data_)
        : uniqueID(uniqueID_)
        , data(data_) {}

private:        
    int uniqueID; 
    double data; 
};


int main() {
    vector<duo> myVector;
    myVector.emplace_back(1, 1.0);
}

Answer 2

If you are using a C++11 compiler, compile the .cpp file using g++ -std=c++11 . Also, remove typedef from the definition of the struct duo .

Otherwise you can create a parameterized constructor for duo and then use the constructor for push_back the duo objects into the vector.

Code:

struct duo {
    int uniqueID; 
    double data; 
    duo(int _uniqueID, double _data) : uniqueID{_uniqueID}, data{_data} {}
};

vector<duo> myVector;
myVector.push_back(duo(1,1.0)); //This compiles.

Hope that helped.