动态2维数组分配

Question

I am creating a dynamic 2 dimensional array and allocating it. My for loop gives an error after 10-15 runs (not same value everytime) with bad allocation. Any help would be appreciated.

__int32 aLarge = 8121432;
__int32 bLarge = 8121784;
ActualPosition** myPositions;

myPositions = new ActualPosition*[aLarge];

for (int x = 0; x < aLarge; x++)
{
    try
    {
        myPositions[x] = new ActualPosition[bLarge];
    }
    catch (bad_alloc& ba)
    {
        // Error here
    }
}

Answer 1

If sizeof(ActualPosition) == 1 then you would need 61,431 GB of memory to hold your array. So you are going to run out of memory unless you have a very large computer.

Answer 2

As you tagged you question with C++ and regardless of the memory size issue raised by @NathanOliver, I would suggest using a library container for two-dimensional arrays.

For example:

std::vector<std::vector<ActualPosition>> myArray(aLarge);
for( auto v: myArray )
   v.resize(bLarge);

Accessing elements will be as simple as:

myArray[i][j] = somevalue;

without bound checking, or use at() if you want something more safe:

myArray.at(i).at(j) = somevalue;

If the size is known at compile time (which seems to be the case in your code), you can also use std::array .