C++ Object 创建时间

Question

So I'm building an A* search sort of thing and creating objects as below when needed within my algorithm. Thing is, they're taking.1 of a second each being created. My search takes 40 seconds, 39 seconds of which is object creation.

I really got no clue. Pretty new. Any help appreciated.

class Node{
private:
    int numAncestors;
    float gvalue;
    float hvalue;
    float fvalue;
    int adj;
    Node* parent;
public:
    inline Node(int vertex, int goal, vector< vector<double> > xy){

        adj = vertex - 1;
        float x1 = (float)xy[vertex-1][0];
        float y1 = (float)xy[vertex-1][1];
        float x2 = (float)xy[goal-1][0];
        float y2 = (float)xy[goal-1][1];
        hvalue = sqrtf((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
        //fvalue = hvalue + gvalue;
    }
    inline float getF(){
        return hvalue + gvalue;
    }

    inline void setG(float newG){
        gvalue = newG;
    }
    inline float getG(){
        return gvalue;
    }

    inline int getAncestors(){

        return numAncestors;
    }

    void setAncestors(int ancestors){

        numAncestors = ancestors;
    }
    void setParent(Node* n, vector< vector<double> > xy){

        parent = n;
        float x1 = (float)xy[n->getAdj()][0];
        float y1 = (float)xy[n->getAdj()][1];
        float x2 = (float)xy[adj][0];
        float y2 = (float)xy[adj][1];
        float x = sqrtf((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));

        setG(n->getG() + x);
        setAncestors(n->getAncestors()+1);
     }

    inline Node* getParent(){

        return parent;
    }

    inline int getAdj(){

        return adj;
    }
};

This takes.1 seconds:

clock_t nodetest = clock();    
Node* s = new Node(g,e,xy);
printf("Time taken: %.2fs\n", (double)(clock() - nodetest)/CLOCKS_PER_SEC);

This takes 0.0 seconds:

clock_t thisLoop = clock();
float x1 = (float)xy[x-1][0];
float y1 = (float)xy[x-1][1];
float x2 = (float)xy[current->getAdj()][0];
float y2 = (float)xy[current->getAdj()][1];
float x = sqrtf((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
printf("Time taken: %.2fs\n", (double)(clock() - thisLoop)/CLOCKS_PER_SEC);

I would have thought maybe it was what the object was up to or whatever, but it seems from that the entirety of the time spent is just in object creation.

Answer 1

When you call the Node constructor, you are passing xy by value , meaning a copy is made of the entire array. You should pass it by const reference :

Node(int vertex, int goal, const vector<vector<double>> &xy)

This should also be done for setParent .

Other notes:

The Node constructor does not initialize all of its members. In particular, parent will have a garbage value in it, which can lead to strange bugs later.

The Node constructor and setParent share a bunch of code that does some work. This should be placed in a (private) member function that can be called to avoid the code duplication.

The various get functions can be const , eg float getF() const; .

You don't need the inline keyword, since any function defined within the class definition is implicitly inline.