bitsets二进制AND运算 [英] bitsets binary AND operation

问题描述

我写了以下行：

  std :: bitset< 4> bitvec; // bitset 0000 
 std :: bitset< 4>加成; // bitset 0000 
 
 addition.set（0）; //设置最低有效位
 
 std :: cout<<添加< std :: endl; // output 0001 
 std :: cout< std :: endl; 
 
 for（int x = 0; x！= 16; ++ x）{//加法循环
 std :: cout< bitvec<< std :: endl; // output 
 bitvec& = addition; // binary and 
} 
 
 std :: cout<< std :: endl; 
  

我希望输出为：

  0000 
 0001 
 0010 
 0011 
 0100 
 0101 
 .... 
  

但是循环只输出'0000'。

解决方案

逻辑AND是不 b
$ b

具体来说，

  0000 
& 0001 
 ------ 
 = 0000 
  

总是获得 0000

$

逻辑AND仅查看两个位组中的每个位，只输出1在其他向量中为1。例如：

  1001 
& 1100 
 ------ 
 = 1000 
  

位是1是因为其他位组中的第一位是1.其余的是0，因为其中一个位组在该位置有一个0。

如果你想添加，不使用bitset，只需使用添加。

  unsigned long a = 0; 
 
 for（int i = 0; i <16; ++ i）
 {
 std :: cout< std :: bitset 4（a）< std :: endl; 
 ++ a; 
} 
  

输出：

  0000 
 0001 
 0010 
 0011 
 0100 
 0101 
 0110 
 0111 
 1000 
 1001 
 1010 
 1011 
 1100 
 1101 
 1110 
 1111 
  

I wrote the following lines:

std::bitset<4> bitvec;  //bitset 0000
std::bitset<4> addition; //bitset 0000

addition.set(0); //setting the least significant bit

std::cout << addition << std::endl; //output 0001
std::cout << std::endl;

for(int x = 0; x != 16; ++x) { //addition loop
    std::cout << bitvec << std::endl; //output
    bitvec &= addition; //binary AND
}

std::cout << std::endl;

and I expected the output to be:

0000
0001
0010
0011
0100
0101
....

But the loop just outputs '0000'. What basic concept am I missing?

解决方案

Logical AND is not addition.

Specifically,

  0000
& 0001
------
= 0000

Which explains why you always get 0000.

Logical AND just looks at each bit in both bitsets and only outputs a 1 if that bit is 1 in both of the other vectors. As an example:

  1001
& 1100
------
= 1000

The reason that first bit is 1 is because the first bit in the other bitsets is 1. The rest are 0 because one of the bitsets has a 0 at that position.

If you want addition, don't use a bitset, and just use addition.

unsigned long a = 0;

for (int i = 0; i < 16; ++i)
{
    std::cout << std::bitset<4>(a) << std::endl;
    ++a;
}

Output:

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

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