Dynamic-memory-allocation.cpp

#include <iostream>
using namespace std;

int main() {
    int sz;
    cout << "enter size: ";
    cin >> sz;
    int* x = new int[sz];
    cout << "allocated " << (sz * sizeof(int)) << " bytes at " << x << endl;
    delete [] x;
    return 0;
}

Multidimensional-memory-allocation.cpp

#include <iostream>

using namespace std;
int main() {
    int sx, sy, sz;
    cout << "enter size (x y z): ";
    cin >> sx >> sy >> sz;
    int*** x = new int**[sx];
    for (int i = 0; i < sx; ++i) {
      x[i] = new int*[sy];
      for (int j = 0; j < sy; ++j) {
        x[i][j] = new int[sz];
      }
    }
    
    cout << "allocated " << (sx*sy*sz * sizeof(int)) << " bytes (not including pointers)";
    for (int i = 0; i < sx; ++i) {
      for (int j = 0; j < sy; ++j) {
        delete [] x[i][j];
      }
      delete [] x[i];
    }
    delete [] x;
    cout << "de-allocated x" << endl;    

    return 0;
}

Static-static-dynamic.cpp

#include <iostream>
#include <assert.h>

#define SX 8
#define SY 20

using namespace std;

int main() {
    int sz;
    cout << "enter size: ";
    cin >> sz;
    assert(sz > 0);

    int* x[SX][SY]; // On the stack
    for (int i = 0; i < SX; ++i)
      for (int j = 0; j < SY; ++j)
        x[i][j] = new int[sz]; // In the heap

    x[2][4][0] = 5; // etc. 
    //^  ^  ^--- This dimension is dynamically allocated
    //|  +-------This dimeision is static, ie. on the stack
    //+----------This dimension is also static (no need for de-allocation)  
        
    // free 
    for (int i = 0; i < SX; ++i) 
      for (int j = 0; j < SY; ++j) 
        delete [] x[i][j];

    return 0;
}