Initialize 2D array of objects

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;
        }
    }

Compiler do not provide default constructor when you have overloaded it. — Mahesh
– Mahesh, Commented Jun 28, 2013 at 13:12
In response to your edit, yes, you can do that. Or you can use a std::vector instead to make things easier. — David G
– David G, Commented Jun 28, 2013 at 13:29
Yes one more Thing hmmm I tried tfreq[i][j]->getTermFrequency() instead of tfreq[i][j].getTermFrequency() and it gave me an error can u explain it why? — Hani Goc
– Hani Goc, Commented Jun 28, 2013 at 13:34

David G · Accepted Answer · 2013-06-28 13:32:13Z

1

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() { ... }
    // ...
};

edited Jun 28, 2013 at 13:32

answered Jun 28, 2013 at 13:11

David G

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Comments

Nick · Accepted Answer · 2013-06-28 13:11:43Z

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

answered Jun 28, 2013 at 13:11

Nick

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2 Comments

Hani Goc Over a year ago

I added a default constructor @Nikola to initialize the array. what am i doing is right?

Nick Over a year ago

@HaniGoc yes, you can test it

Cassio Neri · Accepted Answer · 2013-06-28 13:11:59Z

1

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.

answered Jun 28, 2013 at 13:11

Cassio Neri

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2 Comments

Hani Goc Over a year ago

Ahh. Well i have this contructor TermFrequency(Key,string,int,double); Do i need a default constructor? Sorry if this question is silly

Cassio Neri Over a year ago

Yes, you do need a default constructor: one that accepts an empty list of arguments. Normally the compiler defines one for you but if you define another constructor (as you do) then the compiler will not generate the default constructor and you have to do it manually.

Alexandru Barbarosie · Accepted Answer · 2013-06-28 13:20:50Z

1

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);

edited Jun 28, 2013 at 13:20

answered Jun 28, 2013 at 13:15

Alexandru Barbarosie

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Comments

Mostafa Sultan · Accepted Answer · 2014-12-26 19:11:41Z

1

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

edited Dec 26, 2014 at 19:11

answered Dec 26, 2014 at 8:16

Mostafa Sultan

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