简单的toString（）问题 [英] Simple toString() problem
问题描述
< code snippet>
char * Car :: toString（）
{
//示例[XR，Holden]
char * str = {" ["，carID，"，"，carName，"]"};
返回str;
}
注意：carID和carName是类Car的私有变量
编译错误：标量变量的Car.cpp初始化程序需要一个元素
基本上，toString（）方法不起作用。任何帮助赞赏。注意，
我对使用较新的字符串数据类型不感兴趣，因为我想要
来学习使用指向char的指针。
问候
wewewe
Hi,
<code snippet>
char* Car::toString()
{
//Example [XR, Holden]
char* str = {"[", carID, ",", carName, "]"};
return str;
}
Note: carID and carName are private variables of class Car
Compile Error: Car.cpp initializer for scalar variable requires one element
Basically, the toString() method doesn''t work. Any help appreciated. Note,
I''m not interested in working with the newer string data type because I want
to learnto do it with pointers to char.
Regards
wewewe
推荐答案
Ying Yang写道：
Ying Yang wrote:
<代码片段>
char * Car :: toString（）
{
//示例[XR，Holden]
char * str = {" ["，carID，"，"，carName，"]"};
Hi,
<code snippet>
char* Car::toString()
{
//Example [XR, Holden]
char* str = {"[", carID, ",", carName, "]"};
我看到它的方式，你想要返回类似的东西：
" [carId，carName]"
with当然，carId和carName的真正价值。我假设carId和
carName也是char *。
好吧，
1）{" ["，carID ，，，carName，""}基本上是一个
的数组的语法（如果carId和carName也是char *，可能是char *）。在其他
字样中，如果我们称之为str，其内容为：
str [0] ==" {"
str [1] == carId
str [2] =="，"
str [3] == carName
str [ 4] =="]"
无论如何，它的类型是char * [5]而不是char *，这就是为什么你得到
错误。你试图将一个数组分配给一个标量变量。
2）你怎么能用旧式的东西来做呢：
//首先你会需要一个缓冲区：
char * buf = new char [30]; //让我们说一个30个字符的缓冲区
//然后填充缓冲区
sprintf（buf，" [％s，％s]"，carId ，carName）; // sprintf需要#include< cstdio>
返回buf;
请注意我用new分配了buf，否则它将被销毁为
很快toString（）退出，返回的指针指向无处。
我认为你需要一本好的C ++书。请参阅常见问题解答。
The way I see it, you want to return something like:
"[carId,carName]"
with the real values of carId and carName, of course. I assume carId and
carName are also char*.
Well,
1) {"[", carID, ",", carName, "]"} is basically the syntax for an array of
stuff (presumably char* if carId and carName are also char*). In other
words, if we call it str, its contents are:
str[0] == "{"
str[1] == carId
str[2] == ","
str[3] == carName
str[4] == "]"
Anyway, its type is char*[5] not char*, which is why you are getting the
error. You are trying to assign an array to a scalar variable.
2) How you could do it with old-styled stuff:
//first you would need a buffer:
char * buf = new char[30]; //let''s say a 30 character buffer
//then fill the buffer
sprintf(buf,"[%s,%s]", carId, carName); //sprintf requires #include <cstdio>
return buf;
Notice that I allocated buf with new, otherwise it would be destroyed as
soon as toString() exits and the returned pointer would point to nowhere.
I think you need a good C++ book. See the FAQ.
< code snippet>
char * Car :: toString（）
//示例[XR，Holden]
char * str = { " ["，carID，"，"，carName，"]"};
返回str;
}
注意：carID和carName是私有的类Car的变量
使用ostringstream，并切换到使用std :: string作为返回
Hi,
<code snippet>
char* Car::toString()
{
//Example [XR, Holden]
char* str = {"[", carID, ",", carName, "]"};
return str;
}
Note: carID and carName are private variables of class Car
Use an ostringstream, and switch to using std::string for the return
的值。
ostringstream oss;
oss< ;< ''[''<< carID<< ''，''<< carName<< ]; //就像使用cout
return oss.str（）;
如果你/必须/使用C风格的字符串，你将不得不解决动态问题
内存管理。不过，这是一个完整的讨论。
Josh
value.
ostringstream oss;
oss << ''['' << carID << '','' << carName << '']''; // just like using cout
return oss.str();
If you /must/ use C-style strings, you''re going to have to tackle dynamic
memory management. That''s a whole ''nother discussion, though.
Josh
我需要包含什么才能使用ostringstream oss？使用指向char的指针看起来不像是一个正常的方式。
wewewe
What do i have to include to use ostringstream oss?? doesn''t not seem like a
normal way of doing it with pointers to char.
wewewe
On Sun，07 Sep 2003 23:37:44 +0930，Ying Yang写道：
On Sun, 07 Sep 2003 23:37:44 +0930, Ying Yang wrote:
>
>
> < code snippet>
> char * Car :: toString（）
> {
> //示例[XR，Holden]
> char * str = {" ["，carID，"，"，carName，"]"};
> return str;
> }
>
>注意：carID和carName是类Car的私有变量
使用ostringstream，并切换到使用std :: string作为返回
> Hi,
>
> <code snippet>
> char* Car::toString()
> {
> //Example [XR, Holden]
> char* str = {"[", carID, ",", carName, "]"};
> return str;
> }
>
> Note: carID and carName are private variables of class Car
Use an ostringstream, and switch to using std::string for the return
值。
ostringstream oss;
oss<< ''[''<< carID<< ''，''<< carName<< ]; //就像使用cout
return oss.str（）;
如果你/必须/使用C风格的字符串，你将不得不解决动态问题
内存管理。不过，这是一个完整的讨论。
Josh
ostringstream oss;
oss << ''['' << carID << '','' << carName << '']''; // just like using cout
return oss.str();
If you /must/ use C-style strings, you''re going to have to tackle dynamic
memory management. That''s a whole ''nother discussion, though.
Josh
我需要包含什么才能使用ostringstream oss ??
What do i have to include to use ostringstream oss??
< sstream>。
看起来并不像是指向char的正常方式。
<sstream>.
doesn''t not seem like a
normal way of doing it with pointers to char.
不，它使用C ++风格的字符串，这就是为什么我说要将你的返回
类型转换为std :: string。指向char的指针不是正常的方式，它是C
的方式。在C ++程序中，你应该使用std :: string。
Josh
No, it uses C++-style strings, which is why I said to switch your return
type to std::string. Pointers to char is not the normal way, it is the C
way. In a C++ program, you should use std::string.
Josh
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