初始化2D对象数组

Question

Hi I am having a problem with the initialization of a 2D array of objects. The class is TermFrequency(Key,string,int,double); That's how I initialize the dynamic 2D array of objects:

// TermFrequency tfreq [v_word.size()][totalNumberOfDocuments];
   TermFrequency** tfreq = new TermFrequency*[v_word.size()];
   for(size_t i = 0; i < v_word.size(); ++i)
       tfreq[i] = new TermFrequency[totalNumberOfDocuments];

I understood why i am getting the error:

• no matching function for call to 'TermFrequency::TermFrequency()'|
• note: TermFrequency::TermFrequency(Key, std::string, int, double)|

I just want to know how I can fix it?

Thank you.

Ok I added the DEFAULT Constructor TermFrequency and it worked: TermFrequency(); Now for example I can add new objects like, right?

Is that implementation considered right?

 For(int i = 0; i < Length1; i++){
    for(int j = 0; j < length2;j++){
       tfreq[i][j] = TermFrequency(v_word[i],documents[j],j,wordCount);
    }
    }

And that's for the output:

  for( size_t i = 0 ; i < v_word.size() ; i++ )
    {
        for(int j = 0; j < totalNumberOfDocuments;j++)
        {
             cout << tfreq[i][j].getTermFrequency() << endl;
        }
    }

Answer 1

Replace this

tfreq[i] = new TermFrequency[totalNumberOfDocuments];

with this

tfreq[i] = new TermFrequency(yourKey,totalNumberOfDocuments);

or simply

 tfreq[i] = //create new TeamFrequencyObject by using class constructor

Answer 2

This line

TermFrequency tfreq[v_word.size()][totalNumberOfDocuments];

attempts to default-construct an array of TermFrequency objects. In other words, it will call the default-constructor of all the elements in the array.

The problem is that your TermFrequency class already has a user-defined constructor ( TermFrequency::TermFrequency(Key, std::string, int, double) that overrides the compiler-generated default-constructor. You'll need to include it on your own:

class TermFrequency
{
    public:
         TermFrequency() { ... }
    // ...
};

Answer 3

no matching function for call to 'TermFrequency::TermFrequency()

It looks like your class doesn't have a default constructor and then the line

tfreq[i] = new TermFrequency[totalNumberOfDocuments];

fails to compile.

Answer 4

Since you have overloaded your conctructor TermFrequency(Key,string,int,double); you do not have a default one anymore. And when you call this line

tfreq[i] = new TermFrequency[totalNumberOfDocuments];

your program looks for a default constructor.

In order to avoid the error you have to rewrite your overlaoded TermFrequency constructor as follows:

TermFrequency(Key = Key(),string = " ",int = 0,double = 0);

Answer 5

or Dynamic then you can do the following :

myclass **mc =  new myclass*[5];
 for (int i = 0; i < 5; ++i) 
  mc[i] = new myclass[6];

then you can for loop the 2d mc[i][x] = new myclass ( ); // if you have several constructors , if you have the default one then the previous first loop is enough without calling the constructor in each element , it will be called by default

what i meant is that if you have two constructors

myclass (){
 this->variable = 0 //... etc
}

and another constructor

myclass (int var){
 this->variable = var;
}

if you want all elements to be initialized by the second constructor , then you need to for loop each element like i said :D