问题描述
我正在使用存储在数组中的函数指针,其中的typedef定义了指针,我对应该如何调用函数有些迷惑.
I'm using function pointers stored in an array with a typedef defining the pointer and I'm a little lost on how I'm supposed to call the function.
这是Menu.h部分:
here's the Menu.h part:
typedef void( Menu::*FunctionPointer )();
FunctionPointer* m_funcPointers;
这是Menu.cpp部分:
here's the Menu.cpp part:
Menu::Menu()
: m_running( true )
, m_frameChanged( true )
, m_currentButton( 0 )
, m_numOfButtons( k_maxButtons )
, m_menuButtons( new MenuButton[k_maxButtons] )
, m_nullBtn( new MenuButton( "null", Vector2( -1, -1 ) ) )
, m_frameTimer( 0 )
, m_funcPointers( new FunctionPointer[k_maxButtons])
{
m_timer.start();
clearButtons();
mainMenu();
}
void Menu::enterButton()
{
m_funcPointers[m_currentButton]();//Error here
}
void Menu::mainMenu()
{
m_funcPointers[0] = &Menu::btnPlay;
m_menuButtons[0] = MenuButton("Play", Vector2(0, 0));
m_funcPointers[1] = &Menu::btnHiScores;
m_menuButtons[1] = MenuButton("HiScores", Vector2(0, 1));
m_funcPointers[2] = &Menu::btnExit;
m_menuButtons[2] = MenuButton("Exit", Vector2(0, 2));
}
void Menu::btnPlay()
{
StandardGame* game = new StandardGame();
game->play();
delete game;
}
m_currentButton是用作索引的整数.我不确定如何实际调用该函数,因为上面的行给了我这个错误:
m_currentButton is an integer used as the index. I'm not sure how to actually call the function as the above line gives me this error:
**C2064 term does not evaluate to a function taking 0 arguments**
视觉工作室给我这个:
expression preceding parentheses of apparent call must have (pointer-to-) function type
我不知道如何解决上述问题,也不知道是由于调用函数还是存储函数.预先感谢.
I don't know how to solve the above problem and whether it's due to how I'm calling the function or how I'm storing it.Thanks in advance.
推荐答案
以与调用不在数组中的函数相同的方式在数组中调用函数指针.
You call a function pointer in an array the same way as you would call a function that is not in an array.
您的问题不是如何在数组中调用函数指针.您试图像调用成员函数指针那样调用成员函数指针的问题.
Your problem isn't how to call a function pointer in an array as such. Your problem that you're trying to call a member function pointer as if it were a function pointer.
您可以像这样调用成员函数指针:
You can call a member function pointer like this:
Menu menu; // you'll need an instance of the class
(menu.*m_funcPointers[m_currentButton])();
编辑新的示例代码:由于您在成员函数中,因此您可能打算在 this
上调用成员函数指针:
Edit for the new example code: Since you're in a member function, perhaps you intend to call the member function pointer on this
:
(this->*m_funcPointers[m_currentButton])();
如果您觉得语法难以阅读,我不会怪您.相反,我建议改用 std :: invoke
(自C ++-17起可用):
If you find the syntax painful to read, I won't blame you. Instead, I'll suggest using std::invoke
instead (available since C++-17):
std::invoke(m_funcPointers[m_currentButton], this);
这篇关于从函数指针数组调用C ++函数的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!