Initializing a dynamic memory array in a class

I am new to c++ programming, and this is probably a trivial problem, but I need to construct a variable sized array in a class and transfer text file data into it, see below. Here HISTORYFile >> ClusterCoord[i]; seems to take in the information fine, however when I try to get access to the info in the main program via,

cout << CoordClassExample.ClusterCoord[1] << "\n";

I get a bus error. Please help if you can!

class CoordClass{
public:
    int Entries;
    double * ClusterCoord;
    void set_valuesCoord(ifstream &HISTORYFile,int MolAtomNum, int MolNum);
};

void CoordClass::set_valuesCoord(ifstream& HISTORYFile,int MolAtomNum, int MolNum) {
    Entries=MolAtomNum*MolNum;
    double *ClusterCoord = new double [Entries];

    for (int i=0;i<Ent开发者_如何学运维ries;i++) {
        HISTORYFile.ignore(1000,'\n');      
            HISTORYFile >> ClusterCoord[i];
        cout << ClusterCoord[i] << "\n";
            HISTORYFile.ignore(1000,'\n');
    }
}

---

You have a leak in the set_valuesCoord() function if you call the function twice, unless you somewhere release the resources. That's not the problem but it's a problem. Use a std::vector<>.

class CoordClass {
    // ...
    std::vector<double> ClusterCoord;  // instead of double *ClusterCoord
    // ...
};

What might be the problem is that you don't check whether the double parsed properly. If it didn't then you're accessing uninitialized memory, and that leads to undefined behaviour.

void CoordClass::set_valuesCoord(...)
{
    // ...
    double cluster_coord = 0;
    if( HISTORYFile >> cluster_coord )
        ClusterCoord.push_back(cluster_coord);
    else
        std::cerr << "Error parsing cluster coord.\n";
    // ...
}

---

As an exercise showing the vector way that won't leak among other things:

Further changes would be to remove Entries and use ClusterCoord.size().

class CoordClass{
public:
    int Entries;
    std::vector<double> ClusterCoord;
    void set_valuesCoord(ifstream &HISTORYFile,int MolAtomNum, int MolNum);
};

void CoordClass::set_valuesCoord(ifstream& HISTORYFile,int MolAtomNum, int MolNum) {
    Entries=MolAtomNum*MolNum;
    ClusterCoord.resize(Entries);

    for (int i=0;i<Entries;i++) {
        HISTORYFile.ignore(1000,'\n');      
            HISTORYFile >> ClusterCoord[i];
        cout << ClusterCoord[i] << "\n";
            HISTORYFile.ignore(1000,'\n');
    }
}