我在用C ++编写代码时遇到[错误:抽象类类型的新表达式无效]问题? [英] I am experiencing [error: invalid new-expression of abstract class type] problem while writing a code in C++ ?
本文介绍了我在用C ++编写代码时遇到[错误:抽象类类型的新表达式无效]问题?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
请为我提供该问题的最佳解决方案.
kindly provide me the best possible solution of the problem.
/**************************
* File Implementation of Factory Design Pattern In an Instumetation Requrement ************************************/
#include <iostream>
using namespace std;
enum InstrumentType
{
IT_INPUT=1, IT_OUTPUT
};
enum Dmm_VendorType
{
DMM_TACTRONICS=1, DMM_AGILENT
};
enum Pwm_VendorType
{
PWM_CHROMA=1, PWM_AGILENT
};
///////////////////////////************************************** Library Calsses *****************************************/////////////////////////////////
class Instrument
{
public:
virtual void Instrument_type() = 0;
static Instrument* Create_instrument(int type_in);
};
class Input_Instrument : public Instrument
{
public:
virtual void Measurment_Voltage() = 0;
static Input_Instrument* Create_Dmm(int type_in);
static Input_Instrument* Create_Pwm(int type_in);
void Instrument_type()
{
cout<<"You are in Input Instrument section...."<<endl;
}
};
class Dmm_tactronics : public Input_Instrument
{
public:
void Measurment_Voltage()
{
cout << "This is Tactronic Dmm voltage...." <<endl;
}
};
class Dmm_agilent : public Input_Instrument
{
public:
void Measurment_Voltage()
{
cout << "This is Agilent Dmm voltage...." <<endl;
}
};
class Power_Meter_Chroma : public Input_Instrument
{
public:
void Measurment_Voltage()
{
cout<<"This is chroma Power_Meter voltage....."<<endl;
}
};
class Power_Meter_agilent : public Input_Instrument
{
public:
void Measurment_Voltage()
{
cout<<"This is Agilent Power_Meter voltage....."<<endl;
}
};
class Output_instrument : public Instrument
{
public:
void Instrument_type()
{
cout<<"You are Output instrument section...."<<endl;
}
};
// Factory method to create objects of different types.
// Change is required only in this function to create a new object type
/***************************** For Instrument Name Selection **************************************/
Instrument* Instrument::Create_instrument(int type_in)
{
if (type_in == IT_INPUT)
return new Input_Instrument();
else if (type_in == IT_OUTPUT)
return new Output_instrument();
else
return NULL;
}
/***************************** For DMM Vendor Name Selection **************************************/
Input_Instrument* Input_Instrument::Create_Dmm(int type_in)
{
if (type_in == DMM_TACTRONICS)
return new Dmm_tactronics();
else if (type_in == DMM_AGILENT)
return new Dmm_agilent();
else
return NULL;
}
/***************************** For Power meter Vendor Name Selection **************************************/
Input_Instrument* Input_Instrument::Create_Pwm(int type_in)
{
if (type_in == PWM_CHROMA)
return new Power_Meter_Chroma();
else if (type_in == PWM_AGILENT)
return new Power_Meter_agilent();
else
return NULL;
}
/////////////////////////************************************** Client Calsses *****************************************////////////////////////////////
// Client doesn''t explicitly create objects
// but passes type to factory method Create_instrument(),Create_Dmm(),Create_Pwm().
class client_Instrument
{
public:
client_Instrument()
{
cout<<"Enter Instrument type....."<<endl;
cin >>type_in ;
pInstrument = Instrument::Create_instrument(type_in);
}
~client_Instrument()
{
if (pInstrument)
{
delete[] pInstrument;
pInstrument = NULL;
}
}
Instrument* getInstrumentName()
{
return pInstrument;
}
private:
Instrument *pInstrument;
int type_in;
};
class client_DMM
{
public:
client_DMM()
{
cout<<"Select Dmm Vendor type....."<<endl;
cin >>type_in ;
pInput_DMM_Instrument = Input_Instrument::Create_Dmm(type_in);
}
~client_DMM()
{
if (pInput_DMM_Instrument)
{
delete[] pInput_DMM_Instrument;
pInput_DMM_Instrument = NULL;
}
}
Input_Instrument* get_DMM_InstrumentName()
{
return pInput_DMM_Instrument;
}
private:
Input_Instrument *pInput_DMM_Instrument;
int type_in;
};
class client_PWM
{
public:
client_PWM()
{
cout<<"Select PWM Vendor type....."<<endl;
cin >>type_in ;
pInput_PWM_Instrument = Input_Instrument::Create_Pwm(type_in);
}
~client_PWM()
{
if (pInput_PWM_Instrument)
{
delete[] pInput_PWM_Instrument;
pInput_PWM_Instrument = NULL;
}
}
Input_Instrument* get_PWM_InstrumentName()
{
return pInput_PWM_Instrument;
}
private:
Input_Instrument *pInput_PWM_Instrument;
int type_in;
};
// Driver program
int main()
{
client_Instrument *pclient_Instrument = new client_Instrument();
Instrument * pInstrument = pclient_Instrument->getInstrumentName();
pInstrument->Instrument_type();
client_DMM *pclient_DMM = new client_DMM();
Input_Instrument * pInput_DMM_Instrument = pclient_DMM->get_DMM_InstrumentName();
pInput_DMM_Instrument->Measurment_Voltage();
client_PWM *pclient_PWM = new client_PWM();
Input_Instrument * pInput_PWM_Instrument = pclient_PWM->get_PWM_InstrumentName();
pInput_PWM_Instrument->Measurment_Voltage();
return 0;
}
我尝试过的事情:
我试图实现工厂设计模式，并通过返回新关键字加载子类，该子类实际上包含一个纯虚函数定义.
What I have tried:
I am trying to implement factory design pattern , and loading child class through new key word in return, that child class actually contain a pure virtual function definition.
推荐答案
一个类具有纯虚函数的实例不能被实例化.您必须使用子类 WITH 此重写函数.
您可以在此处找到一些进一步的解释.
了解C ++的概念，并在返回类型和用法中重新考虑该函数.
A class with pure virtual function cant be instanciated. You must use a child class WITH this overriden function.
Some further explanation you will find here.
Learn about the concepts of C++ and rethink that function in return type and usage.
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