C ++从函数定义在main中的类中的函数指针的向量调用函数 [英] C++ calling a function from a vector of function pointers inside a class where the function definition is in main
问题描述
好吧,在我的主要有:
void somefunction
int main()
{
// bla bla bla
SomeClass myclass = SomeClass();
void(* pointerfunc)()= somefunction;
myclass.addThingy(pointerfunc);
//后来我做
myclass.actionWithDiffrentOutcomes();
}
void somefunction()
{
//一些代码
}
和类中:
class SomeClass b $ {
public:
void addThingy(void(* function)());
void actionWithDiffrentOutcomes();
private:
std :: vector< void(**)()>向量函数;
}
SomeClass :: addThingy(void(* function)())
{
vectoroffunctions.push_back(& function);
}
SomeClass :: actionWithDiffrentOutcomes()
{
(* vectoroffunctions [0])();;
}
我是一个新的指针, c ++书,googled,ext。这看起来是正确的,编译,运行,但是当我调用actionWithDiffrentOutcomes()我得到访问冲突。我不知道该怎么办。它似乎是正确的,但有些事显然是错误的。那么当定义在另一个类中时,如何从一个类中调用一个函数?
我这样做,因为我不能硬编码每个选项到一个switch语句。
您的代码几乎是正确的。你的向量错误地拿着指向函数的指针,而不是简单地指向函数的指针。 addThingy
正在将函数
的地址添加到向量$ c $
<$> 更改您的代码,如下所示:
<$> p $ p>
//存储指向函数的指针,而不是
//指向函数指针的指针
std :: vector< void(*)()>向量函数;
SomeClass :: addThingy(void(* function)())
{
//不要使用地址的地址:
vectoroffunctions.push_back功能);
}
此外,在其余代码中有很多语法错误应该停止代码甚至编译。
Alright, in my main i have:
void somefunction();
int main()
{
//bla bla bla
SomeClass myclass = SomeClass();
void(*pointerfunc)() = somefunction;
myclass.addThingy(pointerfunc);
//then later i do
myclass.actionWithDiffrentOutcomes();
}
void somefunction()
{
//some code
}
and in the class:
class SomeClass()
{
public:
void addThingy(void (*function)());
void actionWithDiffrentOutcomes();
private:
std::vector<void (**)()> vectoroffunctions;
}
SomeClass::addThingy(void (*function)())
{
vectoroffunctions.push_back(&function);
}
SomeClass::actionWithDiffrentOutcomes()
{
(*vectoroffunctions[0])();;
}
I'm sort of new-ish to pointers, but I read over my c++ books, googled, ext. and this seems correct, compiles, runs but when I call "actionWithDiffrentOutcomes()" I get an access violation. I'm not sure what to do. it seems correct, but something is obviously wrong. So how can I call a function from within a class when the definition is in another?
I'm doing it this way because i cannot hard-code every option into a switch statement.
Your code is almost correct. Your vector is mistakenly holding pointers to pointers to functions rather than simply pointers to functions. addThingy
is adding the address of the function
pointer in to the vector
, but that pointer goes out of scope in the next line.
Change your code as follows:
//Store pointers to functions, rather than
//pointers to pointers to functions
std::vector<void (*)()> vectoroffunctions;
SomeClass::addThingy(void (*function)())
{
//Don't take the address of the address:
vectoroffunctions.push_back(function);
}
Also, you have a lot of syntax errors in the rest of the code which should stop the code from even compiling.
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