初始化const的问题 [英] Problems with initialization of const
问题描述
感谢您的建议我得到了Accelerated C ++我正在学习
它。我发现在运行时初始化常量
的可能性非常有趣，但看起来我没有把它弄好：
#include< iostream> ;
#include< string>
int main（）
{
std： ：字符串名称;
const std :: string store = name;
std :: cout<< Gimme a name << std :: endl;
std :: cin> name;
std :: cout<< 你写的 <<名称<< std :: endl;
std :: cout<< 商店被设置为 <<商店;
返回0;
}
输出结果为：
Gimme一个名字
Tom
你写了Tom
商店设置为
发生了什么商店的内容？谢谢，
问候，
deltaquattro
Hi,
thanks to your suggestions I got "Accelerated C++" and I''m studying
it. I found very interesting the possibility of initializing constants
at runtime, but it looks like I''m not getting it right:
#include <iostream>
#include <string>
int main ()
{
std::string name;
const std::string store = name;
std::cout << "Gimme a name " << std::endl;
std::cin >name;
std::cout << "You wrote " << name << std::endl;
std::cout << "Store was set to " << store;
return 0;
}
The output is:
Gimme a name
Tom
You wrote Tom
Store was set to
What happened to the content of store? Thanks,
greetings,
deltaquattro
推荐答案
deltaquattro写道：
deltaquattro wrote:
感谢您对我的建议加速C ++ ;我正在学习
它。我发现在运行时初始化常量
的可能性非常有趣，但看起来我没有把它弄好：
#include< iostream> ;
#include< string>
int main（）
{
std： ：字符串名称;
const std :: string store = name;
std :: cout<< Gimme a name << std :: endl;
std :: cin> name;
std :: cout<< 你写的 <<名称<< std :: endl;
std :: cout<< 商店被设置为 <<商店;
返回0;
}
输出结果为：
Gimme一个名字
Tom
你写了Tom
商店设置为
发生了什么商店的内容？谢谢，
Hi,
thanks to your suggestions I got "Accelerated C++" and I''m studying
it. I found very interesting the possibility of initializing constants
at runtime, but it looks like I''m not getting it right:
#include <iostream>
#include <string>
int main ()
{
std::string name;
const std::string store = name;
std::cout << "Gimme a name " << std::endl;
std::cin >name;
std::cout << "You wrote " << name << std::endl;
std::cout << "Store was set to " << store;
return 0;
}
The output is:
Gimme a name
Tom
You wrote Tom
Store was set to
What happened to the content of store? Thanks,
什么内容？你复制了一个空字符串。
What content? You copied an empty string to it.
1月31日，下午1:46，deltaquattro < deltaquat ... @ gmail.comwrote：
On Jan 31, 1:46 pm, "deltaquattro" <deltaquat...@gmail.comwrote:
感谢您的建议我得到了加速 C ++"我正在学习
它。我发现在运行时初始化常量
的可能性非常有趣，但看起来我没有把它弄好：
#include< iostream> ;
#include< string>
int main（）
{
std： ：字符串名称;
const std :: string store = name;
std :: cout<< Gimme a name << std :: endl;
std :: cin> name;
std :: cout<< 你写的 <<名称<< std :: endl;
std :: cout<< 商店被设置为 <<商店;
返回0;
}
输出结果为：
Gimme一个名字
Tom
你写了Tom
商店设置为
商店的内容怎么了？谢谢，
Hi,
thanks to your suggestions I got "Accelerated C++" and I''m studying
it. I found very interesting the possibility of initializing constants
at runtime, but it looks like I''m not getting it right:
#include <iostream>
#include <string>
int main ()
{
std::string name;
const std::string store = name;
std::cout << "Gimme a name " << std::endl;
std::cin >name;
std::cout << "You wrote " << name << std::endl;
std::cout << "Store was set to " << store;
return 0;
}
The output is:
Gimme a name
Tom
You wrote Tom
Store was set to
What happened to the content of store? Thanks,
一个const的值只能设置一次，当它被声明时（const
类成员有点在这种情况下，你初始化
存储到name的值，当时恰好是空的。
移动行''const std :: string store = name;''down down''std :: cin
The value of a const can only be set once, when it''s declared (const
class members are a bit different) and in this case you initializes
store to the value of name, which happens to be empty at that moment.
Move the line ''const std::string store = name;'' down below ''std::cin
> name;''它会起作用。
>name;'' and it will work.
查看上面的代码，似乎你期望一个行为
类似于引用，其中store将是一个只读别名
的名字。要获得此行为，请将商店声明更改为
''const std :: string& store = name;''
-
Erik Wikstr？m
Looking at your code above it seems like you expect a behaviour
similar to that of references, where store would be a read-only alias
of name. To get this behaviour change the declaration of store to
''const std::string& store = name;''
--
Erik Wikstr?m
31 Gen，14：09，Erik Wikstr？m < eri ... @ student.chalmers.sewrote：
On 31 Gen, 14:09, "Erik Wikstr?m" <eri...@student.chalmers.sewrote:
1月31日下午1：46，deltaquattro < deltaquat ... @ gmail.comwrote：
On Jan 31, 1:46 pm, "deltaquattro" <deltaquat...@gmail.comwrote:
[..]
[..]
商店内容发生了什么变化？谢谢，
What happened to the content of store? Thanks,
一个const的值只能设置一次，当它被声明时（const
类成员有点在这种情况下，你初始化
存储到name的值，当时恰好是空的。
移动行''const std :: string store = name;''低于''std :: cin
The value of a const can only be set once, when it''s declared (const
class members are a bit different) and in this case you initializes
store to the value of name, which happens to be empty at that moment.
Move the line ''const std::string store = name;'' down below ''std::cin
name;''它会起作用。
name;'' and it will work.
Erik，
语句。
Hi, Erik,
thank you very much for your useful answer. I''m not still used to the
fact that in C++ you can (in this case, you have to) place declaration
statements among executable statements.
>
查看上面的代码，好像你期望一个行为
类似于引用的行为，其中商店将是一个只读别名
的名称。要获得此行为，请将商店声明更改为
''const std :: string& store = name;''
>
Looking at your code above it seems like you expect a behaviour
similar to that of references, where store would be a read-only alias
of name. To get this behaviour change the declaration of store to
''const std::string& store = name;''
是的，这就是我要找的东西：感谢您指点我/ b
引用，我不知道。
问候，
deltaquattro
Yes, that''s what I was looking for: thanks for pointing me to
references, which I didn''t know.
greetings,
deltaquattro
这篇关于初始化const的问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
