Leaking Memory

[volk]

Will this code leak memory? I hope I deleted the array correctly.

#include <iostream>

using namespace std;

int main()
{
//integers n and m represent the field
//n is rows and m is columns
int n = 5, m = 5;

int** field = new int*[n];

for(int i = 0; i < m; i++)
field = new int[m];

for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
field[j] = '.';




//deleting array row by row
for(int i = 0; i < m; i++);
delete[] field;

//deleting last object
delete[] field;

return 0;
}


Thank you

 

[Alf P. Steinbach]

* volk:

Will this code leak memory? I hope I deleted the array correctly.

#include <iostream>

using namespace std;

int main()
{
//integers n and m represent the field
//n is rows and m is columns
int n = 5, m = 5;

int** field = new int*[n];

for(int i = 0; i < m; i++)

This works as long as m == n, but you probably meant to write n, not m.

field = new int[m];

for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
field[j] = '.';
OK.


//deleting array row by row
for(int i = 0; i < m; i++);

Again, n, not m.

delete[] field;
OK.


//deleting last object
delete[] field;
OK.


return 0;
}

Instead you can do

#include <vector>
using namespace std;

int main()
{
int const n = 5;
int const m = 5;
vector< vector< int > > field( n, vector<int>( 5, '.' ) );

// Here use e.g. field[j]
// Automatically deallocated properly.
}

at least if memory serves me right. If it doesn't work right then check out the
std::vector constructors.

Tip: some typedef's can help too.


Cheers & hth.,

- Alf

 

[Jorgen Grahn]

Will this code leak memory? I hope I deleted the array correctly.

#include <iostream>

using namespace std;

int main()
{
//integers n and m represent the field
//n is rows and m is columns
int n = 5, m = 5;

int** field = new int*[n];

for(int i = 0; i < m; i++)
field = new int[m];

for(int i = 0; i < n; i++)
for(int j = 0; j < m; j++)
field[j] = '.';

//deleting array row by row
for(int i = 0; i < m; i++);
delete[] field;

//deleting last object
delete[] field;

return 0;
}

I don't know, but my standard response to the constant stream of
people having trouble with C arrays: use std::vector and the problem
disappears.

/Jorgen