一个bool变量可以存储超过0x01吗？ [英] Can a bool variable store more than 0x01?

问题描述

#include <iostream>
#include <bitset>

using namespace std;

int main()
{
    bool a = 0x03;
    bitset<8> x(a);
    cout<<x<<endl;

    a = a>>1;
    bitset<8> y(a);
    cout<<y<<endl; 
}

结果是：

00000001    
00000000

不：：

The result is not:

00000011
00000001

如果我从 bool a $ c>到 char ，结果将是第二个。
这意味着我不能在 bool 中存储超过0x01，所有正确的值大于0x01被视为0x01。

If I change the type of a from bool to char, the result will be the second one. It means that I cannot store more than 0x01 in a bool, all right value greater than 0x01 are treat as 0x01.

所有编译器都有此行为？

All compiler has the behavior?

推荐答案

§4.12布尔转换[conv.bool]

§4.12 Boolean conversions [conv.bool]

1算术，无范围枚举，指针或指向成员类型的指针的prval值可以转换为bool类型的prvalue。 零值，空指针值或空成员指针值转换为false ; 任何其他值转换为true 。类型std :: nullptr_t的prvalue可以转换为bool类型的prvalue;则结果值为false。

1 A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. A prvalue of type std::nullptr_t can be converted to a prvalue of type bool; the resulting value is false.

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