我正在使用模板实现自定义堆栈。但是我遇到了一个问题,使我对内存安全性提出了质疑。正常使用时,析构函数可以正常工作,但是在进行单元测试时,它将触发堆破坏。特别是在预期会引发异常的测试上。
所有堆栈代码。
#pragma once
#include "StackOverflowException.h"
#include "StackEmptyException.h"
template <class T>
class Stack
{
public:
const static int MAX_SIZE = 1000;
Stack() : m_array(new T[MAX_SIZE]), m_size(0), m_top(0) {};
Stack(const Stack<T>& _other)
{
m_array = new T[MAX_SIZE];
for(auto i = 0; i < _other.size(); ++i)
{
m_array[i] = _other.m_array[i];
}
m_size = _other.size();
m_top = _other.m_top;
}
~Stack()
{
delete[] m_array;
}
void push(T _item)
{
if (m_size + 1 == MAX_SIZE + 1)
{
throw StackOverflowException();
}
m_array[++m_top] = _item;
++m_size;
}
T pop()
{
if(m_top != 0)
{
--m_size;
T item = m_array[m_top];
--m_top;
return item;
}
throw StackEmptyException();
}
T peek() const
{
if (m_size == 0) throw StackEmptyException();
T item = m_array[m_top];
return item;
}
bool empty() const
{
return m_size == 0;
}
size_t size() const
{
return m_size;
}
private:
T* m_array;
size_t m_size;
int m_top;
};
导致堆损坏的单元测试。
TEST_METHOD(CustomStackPopException)
{
Stack<int> stack;
Assert::ExpectException<StackEmptyException>([&] { stack.pop(); });
}
TEST_METHOD(CustomStackPeekException)
{
Stack<int> stack;
Assert::ExpectException<StackEmptyException>([&] { int a = stack.peek(); });
}
TEST_METHOD(CustomStackOverflowException)
{
Stack<int> stack;
const auto functor = [&]
{
for(auto i = 0; i <= Stack<int>::MAX_SIZE; ++i)
{
stack.push(i);
}
};
Assert::ExpectException<StackOverflowException>(functor);
}
当到达那些测试中的第一个时,它将抛出一个弹出警告,说:
HEAP CORRUPTION DETECTED: after Normal block(#279) at 0x0000020298CBC60.
CRT detected that the application wrote to memory after end of heap buffer.
我尝试在堆上制作堆栈对象,但这会导致相同的错误。
此成员函数
void push(T _item)
{
if (m_size + 1 == MAX_SIZE + 1)
{
throw StackOverflowException();
}
m_array[++m_top] = _item;
++m_size;
}
已经不正确。假设MAX_SIZE等于1且m_size等于0。在这种情况下,m_size +1不等于MAX_SIZE +1且有写法。
m_array[1] = _item;
在分配的数组之外。