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What is the difference between "new" and "malloc" and "calloc" and others in family?
(When) Do I need anything other than "new" ?
Is one of them implemented using any other?
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malloc() function creates a single block of memory of a specific size. calloc() function assigns multiple blocks of memory to a single variable.
The malloc() and realloc() functions are part of dynamic memory; malloc() is used for the memory allocation and realloc() is used for the reallocation of the memory.
new and delete are C++ specific features. They didn't exist in C. malloc is the old school C way to do things. Most of the time, you won't need to use it in C++.
malloc allocates uninitialized memory. The allocated memory has to be released with free.calloc is like malloc but initializes the allocated memory with a constant (0). It needs to be freed with free.new initializes the allocated memory by calling the constructor (if it's an object). Memory allocated with new should be released with delete (which in turn calls the destructor). It does not need you to manually specify the size you need and cast it to the appropriate type. Thus, it's more modern and less prone to errors.
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new/delete + new[]/delete[]:
new/delete is the C++ way to allocate memory and deallocate memory from the heap.new[] and delete[] is the C++ way to allocate arrays of contiguous memory.malloc
realloc way, but can use placement new to re-use the same buffer of datanew and freed with free, nor delete[]
malloc/free + family:
malloc/free/family is the C way to allocate and free memory from the heap.calloc is the same as malloc but also initializes the memorymalloc and freed with delete nor delete[]Also see my related answer here
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