调用指针到成员函数C ++ [英] Calling pointer-to-member function C++
问题描述
我有一个指向一个类中定义的成员函数的指针,例如:
class Example {
void (Example :: * foo)();
void foo2();
};
在我的主代码中,我将foo设置为:
例子* a;
a-> foo =& Example :: foo2;
但是,当我尝试调用foo时:
a-> foo();
我得到以下编译时错误:错误:明显调用的括号之前的表达式必须有到 - )函数类型。我假设我在某处得到语法错误,有人可以指出它对我吗?
将执行:(a-> *(a-> foo))()
(a-> * X)(...)
- 解引用成员函数指针 - a-> * X
对于优先级很重要。
X = a-> foo
>
请参阅ideone 这里了解工作示例
I have a pointer to a member function defined within a class, e.g.:
class Example {
void (Example::*foo)();
void foo2();
};
In my main code, I then set foo as:
Example *a;
a->foo = &Example::foo2;
However, when I try to call foo:
a->foo();
I get the following compile time error: "error: expression preceding parentheses of apparent call must have (pointer-to-) function type". I'm assuming I'm getting the syntax wrong somewhere, can someone point it out to me?
to call it you would do: (a->*(a->foo))()
(a->*X)(...)
- dereferences a member function pointer - the parens around a->*X
are important for precedence.
X = a->foo
- in your example.
See ideone here for working example
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