为什么不演这个？ [英] Why won't this cast?
问题描述
类SORef {...};
class SelectedFORef：public SORef {...};
SOFORef SOCastToSOF（SORef sor）{
SelectedFORef sof = nil;
sof = dynamic_cast< selectedFORef>（sor）;
返回sof;
};
我遇到一个问题，即sor没有被转换为sof（变为零）
即使sor是下面的SelectedFORef。 （我有一个调试方法
详细内容和类型）。
我不是C ++专家。
什么是我做错了吗？
Mark
class SORef {...};
class SelectedFORef : public SORef {...};
SOFORef SOCastToSOF(SORef sor) {
SelectedFORef sof=nil;
sof=dynamic_cast<SelectedFORef>(sor);
return sof;
};
I am getting a problem where sor is not being cast to sof (becomes nil)
even though sor IS a SelectedFORef underneath. (I have a debug method
with details contents and type).
I am not a C++ expert.
What am I doing wrong?
Mark
推荐答案
mark写道：
mark wrote:
class SORef {...};
class SelectedFORef：public SORef {...};
SOFORef SOCastToSOF（SORef sor）{
SelectedFORef sof = nil;
class SORef {...};
class SelectedFORef : public SORef {...};
SOFORef SOCastToSOF(SORef sor) {
SelectedFORef sof=nil;
什么是零？
-
Ian Collins。
What''s nil?
--
Ian Collins.
在文章< 5b ************* @ mid.individual.net> ;,
Ian Collins< ia******@hotmail.com写道：
In article <5b*************@mid.individual.net>,
Ian Collins <ia******@hotmail.comwrote:
mark写道：
mark wrote:
class SORef { ......};
class SelectedFORef：public SORef {...};
SOFORef SOCastToSOF（SORef sor）{
SelectedFORef sof =零;
class SORef {...};
class SelectedFORef : public SORef {...};
SOFORef SOCastToSOF(SORef sor) {
SelectedFORef sof=nil;
什么是零？
What''s nil?
nil == NULL。
Pascal版本的NULL。
nil == NULL.
Pascal version of NULL.
mark写道：
mark wrote:
文章< 5b ************* @ mid.individual.net>，
Ian Collins< ia ****** @ hotmail.comwrote：
In article <5b*************@mid.individual.net>,
Ian Collins <ia******@hotmail.comwrote:
> mark写道：
>mark wrote:
>>类SORef {...};
类SelectedFORef：public SORef {...};
SOFORef SOCastToSOF（SORef sor）{
SelectedFORef sof = nil;
>>class SORef {...};
class SelectedFORef : public SORef {...};
SOFORef SOCastToSOF(SORef sor) {
SelectedFORef sof=nil;
什么是零？
What''s nil?
nil == NULL。
Pascal版本的NULL。
nil == NULL.
Pascal version of NULL.
然后为什么隐藏它？你不能将NULL赋给一个类对象，只能指定一个指针。
你不能将dynamic_cast应用于类对象，只能引用一个
指向一个。
-
Ian Collins。
Then why hide it? You can''t assign NULL to a class object, only a pointer.
You can''t apply a dynamic_cast to a class object, only a reference of a
pointer to one.
--
Ian Collins.
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