标题说明了大部分内容,我该怎么做?我已经在Google上搜索了一下,没有任何东西告诉我它无法完成,但是也没有任何说明如何做到这一点。
在此处获取以下代码段:
#include <cstdio>
#include <memory>
int main(void)
{
struct a_struct
{
char first;
int second;
float third;
};
std::unique_ptr<a_struct> my_ptr(new a_struct);
my_ptr.first = "A";
my_ptr.second = 2;
my_ptr.third = 3.00;
printf("%c\n%i\n%f\n",my_ptr.first, my_ptr.second, my_ptr.third);
return(0);
}
正如能回答这个问题的人已经知道的那样,这行不通,甚至无法编译。
我的问题是我该如何做类似的事情?
使用g ++-7的编译错误看起来像
baduniqueptr6.cpp: In function ‘int main()’:
baduniqueptr6.cpp:15:12: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘first’
my_ptr.first = "A";
^~~~~
baduniqueptr6.cpp:16:12: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘second’
my_ptr.second = 2;
^~~~~~
baduniqueptr6.cpp:17:12: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘third’
my_ptr.third = 3.00;
^~~~~
baduniqueptr6.cpp:19:34: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘first’
printf("%c\n%i\n%f\n",my_ptr.first, my_ptr.second, my_ptr.third);
^~~~~
baduniqueptr6.cpp:19:48: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘second’
printf("%c\n%i\n%f\n",my_ptr.first, my_ptr.second, my_ptr.third);
^~~~~~
baduniqueptr6.cpp:19:63: error: ‘class std::unique_ptr<main()::a_struct>’ has no member named ‘third’
printf("%c\n%i\n%f\n",my_ptr.first, my_ptr.second, my_ptr.third);
^~~~~
答案 0 :(得分:7)
您应该使用->
而不是.
,std::unique_ptr
是smart pointer,其行为与原始指针相似。
my_ptr->first = 'A';
my_ptr->second = 2;
my_ptr->third = 3.00;
printf("%c\n%i\n%f\n",my_ptr->first, my_ptr->second, my_ptr->third);
或者您可以使用operator*
取消对指针的引用,然后可以使用operator.
,这也与原始指针相同。
(*my_ptr).first = 'A';
(*my_ptr).second = 2;
(*my_ptr).third = 3.00;
printf("%c\n%i\n%f\n",(*my_ptr).first, (*my_ptr).second, (*my_ptr).third);
PS:您应该将"A"
(这是c样式的字符串)更改为'A'
(这是char
)。
答案 1 :(得分:0)
取消引用指针时,应使用->
而不是.