是否与工会访问各个位的方法吗？ [英] Is there a way to access individual bits with a union?

问题描述

我写一个C程序。我想，我可以访问作为一个char，但我还可以访问的特定位的变量。我想我可以用一个工会这样的...

I am writing a C program. I want a variable that I can access as a char but I can also access the specific bits of. I was thinking I could use a union like this...

typedef union 
{
    unsigned char status;
    bit bits[8];
}DeviceStatus;

但是编译器不喜欢这样。显然，你不能在一个结构使用位。
所以，我能做些什么呢？

but the compiler doesn't like this. Apparently you can't use bits in a structure. So what can I do instead?

推荐答案

当然，但你真的想使用结构来定义这样的位

Sure, but you actually want to use a struct to define the bits like this

typedef union
{
  struct
  {
    unsigned char bit1 : 1;
    unsigned char bit2 : 1;
    unsigned char bit3 : 1;
    unsigned char bit4 : 1;
    unsigned char bit5 : 1;
    unsigned char bit6 : 1;
    unsigned char bit7 : 1;
    unsigned char bit8 : 1;
  }u;
  unsigned char status;
}DeviceStatus;

然后，你可以访问 DeviceStatus DS; 您可以访问 ds.u.bit1 。此外，一些编译器实际上将让你有一个联盟内的匿名结构，这样你可以访问 ds.bit1 如果您ommit从类型定义的U

Then you can access for DeviceStatus ds; you can access ds.u.bit1. Also, some compilers will actually allow you to have anonymous structures within a union, such that you can just access ds.bit1 if you ommit the u from the typedef.

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