c++ anonymous union,struct -- 匿名联合体和机构体

c++ anonymous union,struct -- 匿名联合体和机构体

结构体和联合体各自的基本用法不赘述，仅说一下他们匿名时访问的情况。如果是token不同，可以直接跨层访问。例子

  1. #include <iostream>
  2. using namespace std;
  4. struct zoo_obj{
  5.         string name;
  6.         union {
  7.                 unsigned int property;
  8.                 struct{ //plant
  9.                         unsigned int
  10.                                 hasLeaf:1,
  11.                                 hasFlower:1,
  12.                                 hasTrunk:1,
  13.                                 hasRattan:1;
  14.                 };
  15.                 struct { //animal
  16.                         unsigned int
  17.                                 isBackbone:1,
  18.                                 isOvipara:1,
  19.                                 hasLags:1,
  20.                                 hasWing:1;
  21.                 };
  22.         };
  24. };
  26. int main(void)
  27. {
  28.         zoo_obj peony = {"peony",0};
  29.         zoo_obj dog = {name:"dog",0};
  30.         dog.hasLags = true;
  31.         /* zoo_obj dog = {name:"dog",property:0};
  32.          * sorry, unimplemented: non-trivial designated initializers
  33.          * not supported
  34.          */
  36.         cout << peony.name << " hasLeaf " << peony.hasLeaf << endl;
  37.         cout << dog.name << " hasLags " << dog.hasLags << endl;
  39. }
输出
  1. peony hasLeaf 0
  2. dog hasLags 1
不支持像列子中name样的指定访问。如果指定了会报错
  1. sorry, unimplemented: non-trivial designated initializers not supported
 
 
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原文地址：https://www.cnblogs.com/timssd/p/4781109.html