如何在c ++中使用ostream打印一个unsigned char作为hex？ [英] how do I print an unsigned char as hex in c++ using ostream?

问题描述

我想使用C ++中的无符号8位变量。 unsigned char 或 uint8_t 就算法而言，这样做是有道理的（这是预期的，因为AFAIK uint8_t 只是 unsigned char 的别名，因此调试器会显示它。

$ b如果我有：

 <$ c如果我在c ++中使用ostream打印输出变量$ c> unsigned char a = 0; 
 unsigned char b = 0xff; 
 cout<<a is<<<<<< <<< hex<< b<< endl; 
  

：

  a是^ @; b是377 
  

而不是

  a是0; b是ff 
  

我尝试使用 uint8_t ，但正如我之前提到的，typedef unsigned char ，所以它也是这样的。如何正确打印我的变量？

编辑：我在我的代码中的很多地方这样做。是否有任何方式，我可以做这个没有每次我想要打印 c c c>

解决方案

我建议使用以下技术：

  struct HexCharStruct 
 {
 unsigned char c; 
 HexCharStruct（unsigned char _c）：c（_c）{} 
}; 
 
 inline std :: ostream& operator<<<<<（std :: ostream& o，const HexCharStruct& hs）
 {
 return（o<< std :: hex< 
} 
 
 inline HexCharStruct hex（unsigned char _c）
 {
 return HexCharStruct（_c）; 
} 
 
 int main（）
 {
 char a = 131; 
 std :: cout<< hex（a）<< std :: endl; 
} 
  

这是写入的简短，具有与原始解决方案相同的效率，您选择使用原始字符输出。它是类型安全的（不使用邪恶宏： - ））

I want to work with unsigned 8-bit variables in C++. Either unsigned char or uint8_t do the trick as far as the arithmetic is concerned (which is expected, since AFAIK uint8_t is just an alias for unsigned char, or so the debugger presents it.

The problem is that if I print out the variables using ostream in C++ it treats it as char. If I have:

unsigned char a = 0;
unsigned char b = 0xff;
cout << "a is " << hex << a <<"; b is " << hex << b << endl;

then the output is:

a is ^@; b is 377

instead of

a is 0; b is ff

I tried using uint8_t, but as I mentioned before, that's typedef'ed to unsigned char, so it does the same. How can I print my variables correctly?

Edit: I do this in many places throughout my code. Is there any way I can do this without casting to int each time I want to print?

解决方案

I would suggest using the following technique:

struct HexCharStruct
{
  unsigned char c;
  HexCharStruct(unsigned char _c) : c(_c) { }
};

inline std::ostream& operator<<(std::ostream& o, const HexCharStruct& hs)
{
  return (o << std::hex << (int)hs.c);
}

inline HexCharStruct hex(unsigned char _c)
{
  return HexCharStruct(_c);
}

int main()
{
  char a = 131;
  std::cout << hex(a) << std::endl;
}

It's short to write, has the same efficiency as the original solution and it lets you choose to use the "original" character output. And it's type-safe (not using "evil" macros :-))

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