C++访问类内的浮点指针 ->访问冲突
Visual C++，Microsoft Visual Studio 2010 Express：
从这个 malloc 访问可以工作：
float* block = (float *)_aligned_malloc(32 * sizeof(float), CACHE_ALIGNMENT);
block[0] = (float)30; // I work fine.
但是当它在这个类中时，它不起作用：
class Test
{
private:
//static const int numberOfElements = 1024;
public:
float* block1;
float* block2;
// Constructor
Test::Test(int nElements)
{
float* block1 = (float *)_aligned_malloc(nElements * sizeof(float), CACHE_ALIGNMENT);
float* block2 = (float *)_aligned_malloc(nElements * sizeof(float), CACHE_ALIGNMENT);
}
// Destructor
Test::~Test(void)
{
_aligned_free(block1);
_aligned_free(block2);
}
};
...
Test testClass = Test(32);
testClass.block1[0] = (float)30; // Access violation!
...
或者如果声明为指针，则相同的事情（这是我第一次尝试的方式）：
Test* testClass = new Test(32);
testClass.block1[0] = (float)30; // Access violation!
什么是当 float* 在类中定义时，我在访问值方面做错了？问题是别的吗？
Visual C++, Microsoft Visual Studio 2010 Express:
Access from this malloc works:
float* block = (float *)_aligned_malloc(32 * sizeof(float), CACHE_ALIGNMENT);
block[0] = (float)30; // I work fine.
But when it is inside this class, it does not work:
class Test
{
private:
//static const int numberOfElements = 1024;
public:
float* block1;
float* block2;
// Constructor
Test::Test(int nElements)
{
float* block1 = (float *)_aligned_malloc(nElements * sizeof(float), CACHE_ALIGNMENT);
float* block2 = (float *)_aligned_malloc(nElements * sizeof(float), CACHE_ALIGNMENT);
}
// Destructor
Test::~Test(void)
{
_aligned_free(block1);
_aligned_free(block2);
}
};
...
Test testClass = Test(32);
testClass.block1[0] = (float)30; // Access violation!
...
Or if declared as a pointer, the same thing (this is how I first tried it):
Test* testClass = new Test(32);
testClass.block1[0] = (float)30; // Access violation!
What am I doing wrong in terms of accessing the values when the float* is define inside a class? Is the problem something else?
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评论（2）
您分配给构造函数的局部变量，而不是成员变量。尝试类似的操作
并检查值以确保分配成功。
You assign to the variables local to constructor, not member variables. Try something like
and check the values to make sure allocation succeeded.
构造函数局部变量
block1和block2的声明隐藏了成员变量block1和block2。使用
g++，您可以使用-Wshadow选项获得警告。对于 Visual Studio，恐怕没有选项可以在变量遮蔽另一个变量时发出警告。The declarations of the variables
block1andblock2local to the constructor shadow the member variablesblock1andblock2.With
g++you can get a warning for this with-Wshadowoption. With Visual Studio I'm afraid there is no option to warn when a variable shadows another one.