The difference between heap and stack?

Source: Internet
Author: User

Management mode: for the stack, is automatically managed by the compiler, without our manual control, for the heap, the release of work by the programmer control, easy to produce memory leak.

Application Size:

stack: under Windows, the stack is the data structure to the low address extension, which is a contiguous area of memory. This sentence means that the top of the stack of the address and the maximum capacity of the stack is the system pre-defined, in Windows, the size of the stack is 2M (also said 1M, in short, is a compile-time determination of the constant), if the request for more space than the stack's remaining space, will prompt overflow. Therefore, the space available from the stack is small.

Heap: A heap is a data structure that extends to a high address and is a discontinuous area of memory. this is because the system is stored with a linked list of free memory address, is naturally discontinuous, and the chain of the list of traversal direction is from the low address to high address. The size of the heap is limited by the valid virtual memory in the computer system. Thus, the space of the heap is more flexible and relatively large.

Fragmentation Issues: for the heap, frequent new/delete is bound to cause memory space discontinuity, resulting in a large number of fragments, so that program efficiency is reduced. for the stack, there is no problem, because the stack is advanced out of the queue, they are so one by one correspondence, so that there will never be a memory block from the middle of the stack popped

allocation method: The heap is dynamically allocated and there are no statically allocated heaps. stacks are allocated in 2 ways: static allocation and dynamic allocation. Static allocations are done by the compiler, such as the allocation of local variables. The dynamic allocation is assigned by the ALLOCA function, but the dynamic allocation of the stack is different from the heap, and his dynamic allocation is released by the compiler without our manual implementation.

allocation efficiency: The stack is the data structure provided by the machine system, the computer will support the stack at the bottom: allocate the address of the special register storage stack, the stack stack has a special instruction execution, which determines the efficiency of the stack is high. The heap is provided by the C + + function library, and its mechanism is very complex.

The difference between heap and stack?

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