C语言学习： 联合体

 

 1 #include <io_utils.h>
 2 
 3 #define OP_PRINT_INT 0
 4 #define OP_PRINT_DOUBLE 1
 5 #define OP_PRINT_STRING 2
 6 
 7 typedef union Operand {
 8   int int_operand; // 4
 9   double double_operand; // 8
10   char *string_operand; // 8
11 } Operand;
12 
13 typedef struct Instruction {
14   int operator;
15   Operand operand;
16 } Instruction;
17 
18 void Process(Instruction *instruction) {
19   switch (instruction->operator) {
20     case OP_PRINT_INT: PRINT_INT(instruction->operand.int_operand);
21       break;
22     case OP_PRINT_DOUBLE: PRINT_DOUBLE(instruction->operand.double_operand);
23       break;
24     case OP_PRINT_STRING: puts(instruction->operand.string_operand);
25       break;
26     default:
27       fprintf(stderr, "Unsupported operator: %d\n", instruction->operator);
28   }
29 }
30 
31 int main() {
32   PRINT_INT(sizeof(Operand));
33 
34   Operand operand; // = {.int_operand=5, .double_operand=2.0};
35   operand.int_operand = 5;
36   operand.double_operand = 2.0;
37   PRINT_INT(operand.int_operand);
38   PRINT_DOUBLE(operand.double_operand);
39 
40   Instruction instruction = {
41       .operator = OP_PRINT_STRING,
42       .operand = {
43           .string_operand = "Hello World!"
44       }
45   };
46 
47   Process(&instruction);
48   return 0;
49 }

 

 

posted @ 2023-02-11 20:08  泥古拉斯赵四  阅读(47)  评论(0)    收藏  举报