kernel iteration through for loop

This is a discussion on kernel iteration through for loop within the C++ Programming forums, part of the General Programming Boards category; Just wondering is there a way of generating dynamic variable in C++ For example could you write a function where ...

  1. #1
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    kernel iteration through for loop

    Just wondering is there a way of generating dynamic variable in C++

    For example could you write a function where you define a kernel size i.e. 33 55 77 and the function
    dynamically generate the kernel rather that hand coding it as below
    Code:
    array[row-1][col-1]
    array[row-1][col]
    array[row-1][col+1]
    
    array[row][col-1]
    array[row][col]
    array[row][col+1]
    
    array[row+1][col-1]
    array[row+1][col]
    array[row+1][col+1]
    This kernel would then be used to iterate through a for loop to calculate the average around row col value


    May not be that clear, and I do apologise

  2. #2
    End Of Line Hammer's Avatar
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    You're right, that wasn't particularly clear! Don't know if this will help, or even if its on the right track:
    Code:
     #include <iostream>
     #include <iomanip>
     
     int main(void)
     {
       int array[3][3];
       
       for (int i = 0; i < 3; i++)
       {
         for (int j = 0; j < 3; j++)
         {
           array[i][j] = i * 10 + j;
         }
       }
       
       for (int i = 0; i < 3; i++)
       {
         for (int j = 0; j < 3; j++)
         {
           std::cout <<"array[" <<i <<"][" <<j <<"] = " 
                     <<std::setw(2) <<std::setfill('0') 
                     <<array[i][j] <<std::endl;
         }
       }
       
       
       return(0);
     }
     
      /*
      Output:
     
      array[0][0] = 00
      array[0][1] = 01
      array[0][2] = 02
      array[1][0] = 10
      array[1][1] = 11
      array[1][2] = 12
      array[2][0] = 20
      array[2][1] = 21
      array[2][2] = 22
     
      */
    If you want dynamic sized arrays, use new/delete, or an STL container (eg vector)
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
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    Here is some of the code I've written

    Code:
    if(BoundryKernal==3){
         std::cout<<"\n Kernal size 3";
          for (int plane=0; plane<1; ++plane) {
    	 for (int col=1; col<numCols-1; ++col) {
    			 for (int row=1; row<numRows-1; ++row) {
    
                             SpatialSumCell[index][col][row]=(array[index][col-1][row-1]+array[index][col-1][row]+array[index][col-1][row+1]+array[index][col][row-1]+array[index][col][row]+array[index][col][row+1]+array[index][col+1][row-1]+array[index][col+1][row]+array[index][col+1][row+1])/9;
                             			 }
             }
          }//end if statement boundrykernal==3
       }//end if
    What i was wondering is it possible to dynamically create these array[][] varibles for example a 5 or 7 cell kernel using C++ while also being able to control the indexing on the array[][] i.e

    Code:
     array[col-?][row-?]
    Last edited by sononix; 08-11-2004 at 01:47 AM.

  4. #4
    Sweet
    Join Date
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    Tucson, Arizona
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    Im not exactully not sure what you are trying to do but maybe you want to look into the STL
    heres a link
    http://www.msoe.edu/eecs/ce/courseinfo/stl/index.htm
    Woop?

  5. #5
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    >>What i was wondering is it possible to dynamically create these array[][] varibles
    Yes, of course.
    Code:
    int **array = new int*[rows];
    for (int x = 0; x < rows; x++) {
      array[x] = new int[cols];
    }
    This creates a simulated array of arrays using dynamic memory. To release the memory you perform the same operations in reverse using delete.
    Code:
    for (int x = 0; x < rows; x++) {
      delete [] array[x];
    }
    delete [] array;
    However, managing your own memory is error prone. A better soution is to use the standard vector container given to you by the standard C++ library.
    Code:
    #include <iostream>
    #include <vector>
    
    int main()
    {
      std::vector< std::vector<int> > v;
    
      v.push_back(std::vector<int>(5, 10));
      v.push_back(std::vector<int>(5, 20));
      v.push_back(std::vector<int>(5, 30));
      for (int x = 0; x < 3; x++) {
        for (int y = 0; y < 5; y++) {
          std::cout << v[x][y] << ' ';
        }
        std::cout << std::endl;
      }
    
      return 0;
    }

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