二进制文字？ [英] Binary literals?

问题描述

在代码中，我有时看到人们以十六进制格式指定常量，如下所示：

  const int has_nukes = 0x0001; 
 const int has_bio_weapons = 0x0002; 
 const int has_chem_weapons = 0x0004; 
 // ... 
 int arsenal = has_nukes | has_bio_weapons | has_chem_weapons; // all of them them 
 if（arsenal& = has_bio_weapons）{
 std :: cout< BIO !! 
} 
  

但是在这里使用十六进制格式没有意义。有没有办法直接做二进制？类似这样：

  const int has_nukes = 0b00000000000000000000000000000001; 
 const int has_bio_weapons = 0b00000000000000000000000000000010; 
 const int has_chem_weapons = 0b00000000000000000000000000000100; 
 // ... 
  

我知道C / C ++编译器不会编译，但必须有一个解决方法？

解决方案

我会使用位移位运算符：

  const int has_nukes = 1<< 0; 
 const int has_bio_weapons = 1<< 1; 
 const int has_chem_weapons = 1<< 2; 
 // ... 
 int dangerous_mask = has_nukes | has_bio_weapons | has_chem_weapons; 
 bool is_dangerous =（country-> flags& dangerous_mask）== dangerous_mask; 
  

它比0的洪水更好。

In code, I sometimes see people specify constants in hex format like this:

const int has_nukes        = 0x0001;
const int has_bio_weapons  = 0x0002;
const int has_chem_weapons = 0x0004;
// ...
int arsenal = has_nukes | has_bio_weapons | has_chem_weapons; // all of them
if(arsenal &= has_bio_weapons){
  std::cout << "BIO!!"
}

But it doesn't make sense to me to use the hex format here. Is there a way to do it directly in binary? Something like this:

const int has_nukes        = 0b00000000000000000000000000000001;
const int has_bio_weapons  = 0b00000000000000000000000000000010;
const int has_chem_weapons = 0b00000000000000000000000000000100;
// ...

I know the C/C++ compilers won't compile this, but there must be a workaround? Is it possible in other languages like Java?

解决方案

I'd use a bit shift operator:

const int has_nukes        = 1<<0;
const int has_bio_weapons  = 1<<1;
const int has_chem_weapons = 1<<2;
// ...
int dangerous_mask = has_nukes | has_bio_weapons | has_chem_weapons;
bool is_dangerous = (country->flags & dangerous_mask) == dangerous_mask;

It is even better than flood of 0's.

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