How do I declare a 2d array in C++ using new

A dynamic 2D array is basically an array of pointers to arrays. Here is a diagram of a 2D array with dimenation 3 x 4.

Algorithm

Begin
   Declare dimension of the array.
   Dynamic allocate 2D array a[][] using new.
   Fill the array with the elements.
   Print the array.
   Clear the memory by deleting it.
End

Example Code

 Live Demo

#include <iostream>
using namespace std;
int main() {
   int B = 4;
   int A = 5;
   int** a = new int*[B];
   for(int i = 0; i < B; ++i)
      a[i] = new int[A];
   for(int i = 0; i < B; ++i)
      for(int j = 0; j < A; ++j)
         a[i][j] = i;
   for(int i = 0; i < B; ++i)
      for(int j = 0; j < A; ++j)
         cout << a[i][j] << "
";
   for(int i = 0; i < A; ++i)
      delete [] a[i];
      delete [] a;
return 0;
}

Output

0
0
0
0
0
1
1
1
1
1
2
2
2
2
2
3
3
3
3
3

Vrundesha Joshi

Updated on 30-Jul-2019 22:30:25

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