int xRes=512, yRes=256;

    float **xtable; // pointer to pointer[s]
    xtable = new float*[yRes]; // a ("column") array to hold 'float *' type pointers

    // each element of the above array points to a 'row' of xRes elements
    for(int i=0;i < yRes;i++) {
      xtable[i] = new float[xRes]; 
    }

    for(int i=0;i < yRes;i++){
       for(int j=0;j < xRes;j++){
           xtable[i][j]=45; // store 45 for pixel data, "for now"
       }
    }

Create an 'array2D' class that encapsulates the above. Your class should contain the following 'protected' members ["protected members are accessible in the class that defines them, AND in classes that inherit from it"]:
• xtable
• xRes
• yRes
It should also contain the following public interface:
• constructor: array2D(xResolution,yResolution)
• getSize(int &xResolution, int &yResolution) ['&' because we want those vars to be SET inside the function, like a 'return' in a way; confusingly, int xResolution&, int yResolution& means the same thing!]
• setValue(x,y,val) [at (x,y), store val (in xtable, y would be the rowID, x, the columnID)]
• val=getValue(x,y) [at (x,y), retrieve val]
Remember to create a destructor function as well :)
Exercise your array2D class as follows, inside main(): CourseNana.COM

array2D *a = new array2D(320,240);
int xRes, yRes;
a->getSize(xRes,yRes);

//NOTE the j,i ordering below (twice), since we specify coords as (x,y) [not (y,x)]
for(int i=0;i < yRes;i++){
   for(int j=0;j < xRes;j++){
       a->setValue(j,i,100); // constant value of 100 at all locations
   }
}
for(int i=0;i < yRes;i++){
   for(int j=0;j < xRes;j++){
       cout << a->getValue(j,i) << " "; 
   }
   cout << endl;
}

delete a;

All the code needs to be in a single Q1.cpp file. CourseNana.COM

class PGMImage: public array2D {
   // private:
   // ...
   // protected:
   // ...
   // public:
   // ... 
};//PGMImage