C ++：两个动态数组导致内存分配错误

Question

Here is my code:

int main()
{
    int length = 10;
    int* H = new int(length);
    for(int i=0;i<length;i++)
    {
         H[i] = 0;
    }
    for(int i=0;i<length;i++)
        cout << i << ": " << "\t" << H[i] << "\n";

    double* dos = new double(length);
    for(int i=0;i<length;i++)
    {
        dos[i] = 1.0;
    }
    for(int i=0;i<length;i++)
         cout << i << ": " << dos[i] << "\t" << H[i] << "\n";
    return 0;
}

I'm trying to create an array of doubles that all equal 1.0 and an array of ints that all equal 0. When I run this code it correctly outputs the dos array, but then I get this error

lattice3d: malloc.c:2451: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. Aborted (core dumped)

If I try to initialize the two arrays at the same time, I don't get a memory error, but the arrays end up with weird values within them (ex: the H array looks like [0,0,0,0,0,0,0,0,0,1247506] or something to that effect). Moving where I set all the values of H and dos, changes which values are incorrect.

Answer 1

You are allocating an int not an array:

int* H = new int(length);

should be:

int* H = new int[length];

same with your double case:

double* dos = new double(length);

should be:

double* dos = new double[length];

what you are doing if it were allocated on the stack is int H(10); which is like int H = 10; , and the same for your double case; double dos(10) is like double dos = 10 .

You also are leaking the arrays/values you are creating, and need to call delete[] at the end of your program (note this would be after you do the corrections above):

delete[] H;
delete[] dos;

Since this is tagged C++ and you are using new , it would be worth noting that in modern C++ that is usually best to avoid using new when possible. Here, it would be better to use std::vector than a dynamically allocated array. There is pretty much always a better option to use than new that usually involves using something from the standard library.