blocks|key|4139077|text|由于函数原型不同(一个使用ParentClass，另一个使用ChildClass)，它们不是相同的函数。相反，带有ChildClass参数的函数是重载的，并且不会覆盖Delete函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4139078|entityMap^0|D|B|U|A|1L|A|2B|6|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

As the function prototype differs (one uses <code>ParentClass</code> and the other <code>ChildClass</code>) they are not the same functions. Instead the one with the <code>ChildClass</code> argument is overloading and not overriding the <code>Delete</code> function.

blocks|key|2307332|text|C%2B%2B03标准版:+10.3/2|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2307333|2307334|如果虚拟成员函数vf在类Base和类Derived+(直接或间接派生自Base+)中声明，则声明与vf+具有相同名称和相同参数列表的成员，则Derived::vf也是虚拟的，它覆盖Base::vf。|blockquote|CODE|2307335|2307336|2307337|请注意粗体文本。|2307338|仅当派生类函数具有与基类函数相同的签名(+除外)时，派生类函数才重写基类函数。由于您的函数Delete()在基类和派生类中不具有相同的签名，因此派生类函数不会覆盖基类函数，但您得到的仅仅是。|2307339|C%2B%2B03标准版:+3.3.7/1:|2307340|2307341|名称可以通过在嵌套声明区域或派生类中显式声明相同的名称来隐藏。|2307342|2307343|entityMap^0|0|G|0|0|8|2|C|4|I|7|Z|4|1D|2|1Y|B|2I|8|1G|1B|0|0|0|0|8|0|0|2N|19|8|0|0|I|0|0|0|V|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|11|8|@]|D|@]|E|$]]|$1|G|3|H|5|I|7|12|8|@$9|13|A|14|B|J]|$9|15|A|16|B|J]|$9|17|A|18|B|J]|$9|19|A|1A|B|J]|$9|1B|A|1C|B|J]|$9|1D|A|1E|B|J]|$9|1F|A|1G|B|J]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|K|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1L|8|@$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|1O|8|@$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|J]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1T|8|@$9|1U|A|1V|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1W|8|@]|D|@]|E|$]]|$1|T|3|U|5|I|7|1X|8|@$9|1Y|A|1Z|B|C]]|D|@]|E|$]]|$1|V|3|-4|5|6|7|20|8|@]|D|@]|E|$]]|$1|W|3|-4|5|6|7|21|8|@]|D|@]|E|$]]]|X|$]]

C++03 Standard: 10.3/2 

<blockquote>
 If a virtual member function <code>vf</code> is declared in a class <code>Base</code> and in a class <code>Derived</code>, derived directly or indirectly from <code>Base</code>, a member function <code>vf</code> with the same name and same parameter list as <code>Base::vf</code> is declared, then <code>Derived::vf</code> is also virtual an it overrides <code>Base::vf</code>.
</blockquote>

Note the text in bold. 
An derived class function overides a Base class function only and only if it has the same signature as the Base class function with the exception of <a href="http://msdn.microsoft.com/en-us/library/8z9feath%28v=vs.80%29.aspx" rel="nofollow">Co-Variant return types</a>. Since your function <code>Delete()</code> does not have the same signature in Base Class and Derived class, the derived class function is not overidding the Base class function but what you get is merely <a href="http://www.parashift.com/c++-faq/hiding-rule.html" rel="nofollow">Function Hiding</a>.

C++03 Standard: 3.3.7/1:

<blockquote>
 A name can be hidden by an explicit declaration of that same name in a nested declarative region or derived class.
</blockquote>

blocks|key|4139244|text|因为作为基类函数的参数接受的任何类型，也必须被该函数的重写所接受。这样可以防止出现以下错误：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4139245|struct+BastardClass+:+ParentClass+{}+wrong;
Delete(&wrong);|code-block|syntax|javascript|4139246|如果将其调度到需要ChildClass的重写，将导致它将对象解释为错误的类型。|offset|length|style|CODE|4139247|(这称为逆方差-被更具体的类型覆盖的函数的参数不能比被覆盖的参数更具体。出于类似的原因，返回类型必须是协变的-由更具体的类型覆盖的函数指定的返回类型必须不低于特定类型。)|4139248|entityMap^0|0|0|9|A|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Because any type that's accepted as an argument for the base-class function, must also be acceptable by an override of that function. This prevents an error such as:

<pre><code>struct BastardClass : ParentClass {} wrong;
Delete(&amp;wrong);
</code></pre>

which, if dispatched to the override that expects a <code>ChildClass</code>, would cause it to interpret the object as the wrong type.

(This is known as contravariance - arguments to a function overridden by a more specific type must be no more specific than those being overridden. For similar reasons, return types must be covariant - those specified by a function overridden by a more specific type must be no less specific.)

Say if I have an interface with virtual methods, but one of the arguments are:

<pre><code>virtual void Delete(ParentClass *parentClass) = 0;
</code></pre>

If I later implement this in child class

<pre><code>void Delete(ChildClass *childClass)
{
};
</code></pre>

...why doesn't this work as an implementation?

Implementation of inherited class' method (param=pointer to parent) in child class (param=pointer to child)

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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假设我有一个带有虚方法的接口，但其中一个参数是：virtual void Delete(ParentClass *parentClass) = 0;如果我稍后在子类中实现它void Delete(ChildClass *childClass){};...why不是作为一个实现来工作的吗？

问在子类(param=pointer到子类)中实现继承类的方法(从param=pointer到父类)
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问在子类(param=pointer到子类)中实现继承类的方法(从param=pointer到父类)EN