CODEWITHSUNDEEP
c++memory-leaksstdlist
dem246
dem246

Reputation: 3

Memory leak in using a list of lists

I had some code thrown at me to 'productionize.' I ran a memory leak checker and it calls out the following line within the 'for' loop below as a memory leak.

someStruct->arrayMap = new std::list<BasisIndex>*[someStruct->mapSizeX];
for(int i=0; i<someStruct->mapSizeX; i++){  
    someStruct->arrayMap[i] = new std::list<BasisIndex>[someStruct->mapSizeY];
}

Here is how the array map is declared:

struct SomeStruct{
    int mapSizeX;
    int mapSizeY;
    std::list<BasisIndex>** arrayMap;
};

Here are a couple usages of it:

someStruct->arrayMap[xVal][yVal].push_back(tempIndex);

for(it = someStruct->arrayMap[xVal][yVal].begin(); it != someStruct->arrayMap[xVal][yVal].end(); it++){
    ...
}

The memory leak checker dumped for 5 minutes before I killed it. Then I added the following bit of code in a cleanup routine but it still dumps out 150 warnings all pointing to the line of code within the for loop at the top.

for(int x=0; x<someStruct->mapSizeX; x++){
    for(int y=0; y<someStruct->mapSizeY; y++){
        someStruct->arrayMap[x][y].clear();
        someStruct->arrayMap[x][y].~list();
    }
}

std::list<BasisIndex> ** temp = someStruct->arrayMap;
delete temp;

How do I completely delete the memory associated with this array map?

Upvotes: 0

Views: 471

Answers (2)

Billy ONeal
Billy ONeal

Reputation: 106589

someStruct->arrayMap[x][y].~list(); <-- You should not call the destructor manually. (I didn't even know it was valid to do it that way when placement new wasn't used first...) You need to use delete instead.

Upvotes: 3

Marlon
Marlon

Reputation: 20312

Deallocate the objects in the reverse order that you allocated them.

Allocation:

someStruct->arrayMap = new std::list<BasisIndex>*[someStruct->mapSizeX];
for(int i=0; i<someStruct->mapSizeX; i++){  
    someStruct->arrayMap[i] = new std::list<BasisIndex>[someStruct->mapSizeY];
}

Deallocation:

for (int i=0; i<someStruct->mapSizeX; i++){
    delete[] someStruct->arrayMap[i];
}
delete[] someStruct->arrayMap;

Upvotes: 3

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