Declaring and initializing a global 2D array - c++

Question

//gives the error expecting a declaration
int** my_array;
for (int i=0; i<200; i++)
{
my_array[i]= new int [200];
}
//initialize array with zeroes
for (int i = 0; i<200; i++)
{
for (int j = 0; j<200; j++)
{
my_array[i][j] =0;
}
}
In brief:
The 2D array is declared globally
It is initialized in the main. The main calls a function that saves 0's or 1's in specific cells of the array
The array is then printed by the main
Also advice whether the flow is correct?

Answer 1

If you want an array of an array of 200 bools, you could use std::array and std::bitset.
#include <bitset>
#include <array>
//...
std::array<200, std::bitset<200>> my_array;
Second, your code, even if you fix the syntax error is wrong. You would need to create my_array this way:
int** my_array;
//...
my_array = new int * [200];
for (int i = 0; i < 200; ++i )
my_array[i] = new int [200];
Then somewhere you have to delete this memory:
for (int i = 0; i < 200; ++i )
delete [] my_array[i];
delete [] my_array;
An alternate that creates a contiguous block and uses only two calls to new[]:
my_array = new int * [200];
int *pool = new int [200*200];
for (int i = 0; i < 200; ++i, pool += 200 )
my_array[i] = pool;
Then somewhere you have to delete this memory:
delete [] my_array[0];
delete [] my_array;
However I advise you use a container such as the std::array, std::bitset, std::vector, etc. instead of the int** approach.

Answer 2

Regarding your syntax error, it's probably due to something before the code you have shown.
The shown code,
int** my_array;
for (int i=0; i<200; i++)
{
my_array[i]= new int [200];
}
//initialize array with zeroes
for (int i = 0; i<200; i++)
{
for (int j = 0; j<200; j++)
{
my_array[i][j] =0;
}
}
compiles fine as the body of a function.
Regarding the logic, which is incorrect and which uses troublesome constructs,
do this:
auto my_array = vector<vector<bool>>( 200, vector<bool>( 200 ) );
where vector is std::vector from the <vector> header.
This avoids the raw pointers, the new-ing`, the loops, etc., all that you find problematic.
Alternatively you can declare it like this:
vector<vector<bool>> my_array( 200, vector<bool>( 200 ) );
Note that a global variable is usually troublesome, best avoided.