This isn't exactly a thread about a particular question, but a thread that may help people with memory dynamically allocated/deallocated during runtime. The below example goes over pointers in multiple dimensions--
#include <cstdlib>
#include <iostream>
/**
This program can be used to determine whether pointers are deleted
or not by the end of the program.
This will be a good tool to determine how to delete objects.
*/
using namespace std;
class MemoryManager{
private:
int index;
static int x;
public:
MemoryManager(){
index = x++;
cout << "Creating class: " << index << endl;
}
~MemoryManager(){
cout << "Deleting value. Now " << --x;
cout << " objects remain."<< endl;
}
int getIndex(){return index;}
static void showRemaining(){
cout << "The total amount of existing objects are: ";
cout << x << endl;
}
};
int MemoryManager::x = 0;
/*
*Below are several cases I made up on my own for multi-dimensional pointers.
*A fair warning: DO NOT USE ALL CASES AT ONCE! Doing so WILL cause damange to
*the heap! Be very careful with this program.
**/
int main(int argc, char *argv[])
{
//To be commented out for the below cases
/*
MemoryManager **mm = new MemoryManager*[5];
for(int i = 0; i < 5; i++)
{
mm[i] = new MemoryManager[2];
}*/
//Solution
//case 1, apparantly the correct case
/*
{
for(int i = 0; i < 5; i++)
{
delete[] mm[i]; //[rows] of the pointer mm
//can be thought of as deleting the last array of values at the [ith] location
}
}*/
//Memory leak
//case 2, seems like a logical unwrapping process, but watch what happens
/*
{
for(int i = 0; i < 5; i++)
{
delete mm[i];
}
delete mm;
}*/
//WARNING! Heap Damage can be done with this statement!
//case 3, DANGEROUS! Avoid this at all costs!
/*
{
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 2; j++)
{
delete &mm[i][j];
}
}
}*/
//Memory leak
//case 4, a typical and lazy approach to a problem
/*
{
delete[] *mm; //only gets rid of the first 2 elements located at mm[0]
delete mm; //this statement literally does nothing
}*/
// MemoryManager::showRemaining();
//-----------------------------------------------------------------------------
//now to make a 5 * 4 * 3, triple dimension pointer (60 values)
MemoryManager ***mm2 = new MemoryManager**[5];
for(int i = 0; i < 5; i++)
{
mm2[i] = new MemoryManager*[4];
for(int j = 0; j < 4; j++)
{
mm2[i][j] = new MemoryManager[3];
}
}
//Solution
//case 1, the correct way
{
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 4; j++)
{
delete[] mm2[i][j]; //[rows][columns] of the pointer
//can be thought of as deleting the entire array of values at the [ith][jth] location
}
}
}
MemoryManager::showRemaining();
cin.get();
return 0;
}I'd like to add it as a snippet but I'm sure that more scenarios can be introduced to promote memory management.
