c_cpp 在C中使用union中的str对象

Posted 2021-05-14

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//using string inside union

typedef struct {
  char* begin;
  char* end;
} String;


typedef union {
  int num;
  String string;
  long* count;
} Value;


int main(void) {
  Value val;
  printf("size of union %lu\n", sizeof(Value));
  char* mes = "hello";
  val.string.begin = malloc(5);
  val.string.end = val.string.begin + 5;
  memcpy(val.string.begin, mes, 5);
  printf("%.*s\n", 5, val.string.begin);
  return 0;
}