使用 VS2010 的 C++ 中的位集 [英] bitsets in C++ using VS2010

问题描述

我不知道我在这里做错了什么，希望这里有人能启发我.

我有一个 Flags 类，这是一个极其简化的版本，但我声明了一个位集

类标志{私人的://8位列表std::bitset<8>_P;民众:标志()；}

在我的构造函数中，我将其初始化为

Flags::Flags():_P(32ul){}

但它不会编译并给我错误

<块引用>

错误 C2668:'std::bitset<_Bits>::bitset':对重载函数

这是在 VS2010 SP1 64 位编译，但作为 32 位程序

编辑

接受的答案是上述但作为旁注，任何人都可以解释为什么在使用默认构造函数(应该将它们全部初始化为零)时，它们并未全部设置为零?

_p.to_ulong()

返回 1390560944和 _p 看起来像

[8](0,0,0,0,1,1,0,1)

解决方案

根据 http://connect.microsoft.com/VisualStudio/feedback/details/532897/problems-constructing-a-bitset-from-an-unsigned-long-in-the-vc-rc

另请注意，以 _ 和大写字母开头的标识符是为实现保留的，在您的程序中使用是非法的.

根据变通方法页面(如果我没看错的话)，变通方法是将您的值转换为 unsigned long long 而不是 unsigned long.

I can't figure out if I'm doing anything wrong here, hopefully someone here can enlighten me.

I have a class Flags, this is an extremely simplified version but I declare a bitset

class Flags
{
private:
    //List of 8 bits
    std::bitset<8> _P;
public:
    Flags();
}

On my constructor I initialise it as

Flags::Flags()
    : _P(32ul)
{}

But it won't compile and gives me the error

error C2668: 'std::bitset<_Bits>::bitset' : ambiguous call to overloaded function

This is compiled in VS2010 SP1 64 bit but as a 32bit program

EDIT

Accepted answer is for the above but as a side note could anyone explain why when using the default constructor (which should initialise them all to zero's) they aren't all set to zero's?

_p.to_ulong()

returns 1390560944 and _p looks like

[8](0,0,0,0,1,1,0,1)

解决方案

It's a bug in VC according to http://connect.microsoft.com/VisualStudio/feedback/details/532897/problems-constructing-a-bitset-from-an-unsigned-long-in-the-vc-rc

Also note that identifiers starting with _ and a capital letter are reserved for the implementation and illegal to use in your program.

EDIT: According to the workaround page (if I read it right), the workaround is to cast your value to unsigned long long instead of unsigned long.

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