dynamic-allocation

Possible Duplicate: How do I correctly set up, access, and free a multidimensional array in C? I am trying to dynamically allocate memory for a 2D array using calloc. The columns are fixed as 2 so its only the rows that are dynamic. Here is what I have been trying : unsigned int **pts, rows; int main() { //some code pts = (unsigned int **)calloc(2*rows, sizeof (unsigned int **)); } //The code to access the array : for(k=1;k<=i;k++) { printf("\nX%d=",k); scanf("%d",&pts[k][0]); printf("\nY%d=",k); scanf("%d",&pts[k][1]); } But the problem is, while accessing the array, the program crashes. I am

What is the good way (understand idiomatic/good practice) to dynamically create a multidimensional array in C++. For example let say I have tree integers w , h and d and I want to create an array MyEnum my_array[w][h][d] . (Of course w, h and d are not known at compile time). Is it best to use nested std::vector or use new or something ? Bonus question : Is it possible to set the dimension dynamically too ? bnaecker In general, nesting std::vector is not a great idea. It's usually a better plan to allocate memory which will hold the entirety of your multidimensonal array as a contiguous block,

I'm using a C++ base class and subclasses (let's call them A and B for the sake of clarity) in my embedded system. It's time- and space-critical, so I really need it to be kind of minimal. The compiler complains about lack of a virtual destructor, which I understand, because that can get you into trouble if you allocate a B* and later delete the pointer as an instance of A* . But I'm never going to allocate any instances of this class. Is there a way I can overload operator new() such that it compiles if there's no dynamic allocation of either class, but causes a compiler error if an end user

Suppose we have: int** myArray = new int*[100]; for(int i = 0; i < 100; i++){ myArray[i] = new int[3]; } What is the appropriate way to deallocate this array (which method below, if either is a correct way to do so)? 1. delete[] myArray; 2. for(int i = 0; i < 100; i++){ for(int j = 0; j < 3; j++){ delete myArray[i][j]; } } delete[] myArray; Intuitively it seems like we should do something like 2. since we want all of the memory we allocated to be deleted, but I'm not sure. You used one loop to create it, you should use one loop to delete it. The order is reversed to the order of allocation:

Is std::array<int,10> (without myself using new ) guaranteed to be allocated in the stack rather then the heap by the C++-Standard? To be clear, I do not mean new std::array<int, 10> . I mainly wonder, if the standard library is allowed to use new inside its implementation. I could not find more explicit answer in the standard, but [array.overview]/2 : An array is an aggregate ( [dcl.init.aggr] ) that can be list-initialized with up to N elements whose types are convertible to T . And [dcl.init.aggr]/1 : An aggregate is an array or a class (Clause [class] ) with no user-provided , explicit, or