我每次编译时都会收到LNK 2019和2001错误。 LNK2019声明：
public: __thiscall ColMbr::ColMbr(unsigned int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0ColMbr@@QAE@IV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function "public: __thiscall Alumni::Alumni(unsigned int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int,int,int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0Alumni@@QAE@IV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@HHH0@Z
因此，将ColMbr类与Alumni链接时会出现某种错误。 LNK2011说：
"public: virtual void __thiscall Alumni::addClass(unsigned int,unsigned int)" (?addClass@Alumni@@UAEXII@Z)
因此我的虚拟函数调用存在问题。我知道LNK错误意味着有一个变量需要声明，我错过了但我没有看到它。首先，Alumni :: addClass函数就是为了确保校友不会像ColMbr那样成为一个抽象类，它来自它。其次，校友中的所有论点都是在校友或ColMbr中定义和宣布的。
如果有什么我说LNK2019可能是我的const unsigned int idNbr的问题。我不知道LNK2001有什么问题。也许我需要给函数一个垃圾目的或什么。
这是我的头文件，后跟cpp。
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
#ifndef _ColMbr
#define _ColMbr
class ColMbr
{
protected:
const unsigned int idNbr;
std::string name;
public:
ColMbr();
ColMbr(const unsigned int idNbr, std::string stdnt_name);
std::string setName(std::string stdnt_name);
virtual void display(void);
virtual void addClass(unsigned int credits, unsigned int gradePoint) = 0;
};
#endif // !1
std::string ColMbr::setName(std::string stdnt_name)
{
name = stdnt_name;
return name;
}
class Student : public ColMbr
{
private:
unsigned int credHrs, qualPts;
std::string degSought;
double GPA;
public:
Student(unsigned int idNbr, std::string name) : ColMbr (idNbr, name)
{
credHrs = 0;
qualPts = 0;
degSought = "Unspecified";
}
Student(const unsigned int idNbr, std::string stdnt_name, unsigned int credHrs1, unsigned int qualPts1, std::string newDegree) : ColMbr(idNbr,stdnt_name)
{
credHrs = credHrs1;
qualPts = qualPts1;
degSought = newDegree;
}
void setDegree(std:: string newDegree);
double getGPA(unsigned int credHrs, unsigned int qualPts);
void addClass(unsigned int newClass, unsigned int newQualPts)
{
credHrs = credHrs + newClass;
qualPts = qualPts + newQualPts;
}
void display(void)
{
std::cout << "This student is active." << std::endl <<"ID #: "
<< idNbr << std::endl << "Name: " << name << std::endl
<< "GPA: " << GPA << std::endl << "Major: " << degSought
<< std::endl;
}
};
void Student::setDegree(std:: string newDegree)
{
degSought = newDegree;
}
double Student::getGPA(unsigned int credHrs, unsigned int qualPts)
{
double credHrs1, qualPts1;
std::istringstream input(credHrs);
input >> credHrs1;
std::istringstream input1(qualPts);
input >> qualPts1;
GPA = qualPts1 / credHrs1;
return GPA;
}
#ifndef _Alumni
#define _Alumni
class Alumni : public ColMbr
{
private:
std::string degree;
int month, day, year;
public:
Alumni(const unsigned int idNbr, std::string stdnt_name, int gradMonth, int gradDay, int gradYear, std::string newDegree) : ColMbr(idNbr, stdnt_name)
{
degree = newDegree;
month = gradMonth;
day = gradDay;
year = gradYear;
}
void addClass(unsigned int credits, unsigned int gradePoint);
void display (void)
{
std::cout << "This student is an Alumni." << std::endl <<"ID #: "
<< idNbr << std::endl << "Name: " << name << std::endl
<< "Graduation Date: " << month << "/" << day << "/" << year
<< std::endl << "Major: " << degree << std::endl;
}
};
#endif
/ * ** * ** * ** * ** * ** * ** * ** * ** * ** * ** * ** * ** * ** * ** * ***
#include <iostream>
#include <cstdlib>
#include "ColMbrs.h"
int main()
{
ColMbr *cMbr[4]; // array of base-class pointers
int i; // index to array
// Create some college members
cMbr[0] = new Student( 12345, "Steven DiFranco", 15, 33, "AA" );
cMbr[1] = new Alumni( 98765, "Don Green", 12, 15, 1978, "AAS" );
cMbr[2] = new Alumni( 24680, "Henry Thoreau", 5, 22, 1846, "AA" );
cMbr[3] = new Student( 13579, "Millenia Best" );
// display the array
cout << "All college members:\n";
for( i = 0; i < 4; ++i )
{
cMbr[i]->display(); // no need to check type field or cast
cout << endl;
}
// test addClass for student
cMbr[3]->addClass( 3, 12 );
cMbr[3]->display();
cout << endl;
system("PAUSE");
return 0;
}
答案 0 :(得分：0)
所以，这就是我编写代码并正确运行的方法。
我声明了构造函数和函数，这些函数在课外给我提问。之后，我不得不将GPA的GPA功能分配到Student::display(void)功能。最后，我无法弄清楚如何从const unsigned in idNbr构造函数初始化ColMbr类中的ColMbr(const unsigned int idNbr, std::string stdnt_name)，所以我从变量中取出了const标签。
这是头文件的代码。 .cpp保持不变。
编辑以反映我如何解决const unsigned int idNbr问题。
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
#ifndef _ColMbr
#define _ColMbr
class ColMbr
{
protected:
unsigned const int idNbr;
std::string name;
public:
//A default and initial constructor are called.
ColMbr();
ColMbr(const unsigned int id, std::string stdnt_name) : idNbr(id)
{
name = setName(stdnt_name);
}
virtual ~ColMbr();
std::string setName(std::string stdnt_name);
//ColMbr is made into an abstract class. It can not be called except with
//a pointer.
virtual void display(void);
virtual void addClass(unsigned int credits, unsigned int gradePoint) = 0;
};
#endif // !1
ColMbr::~ColMbr(){}
void ColMbr::display(void)
{
}
std::string ColMbr::setName(std::string stdnt_name)
{
name = stdnt_name;
return name;
}
class Student : public ColMbr
{
private:
unsigned int credHrs, qualPts;
std::string degSought;
double GPA;
public:
//A constructor with no additional Student attributes is created.
Student(unsigned int idNbr, std::string name) : ColMbr (idNbr, name)
{
credHrs = 0;
qualPts = 0;
degSought = "Unspecified";
}
//A constructor that adds Student attributes is created.
Student(const unsigned int idNbr, std::string stdnt_name, unsigned int credHrs1, unsigned int qualPts1, std::string newDegree) : ColMbr(idNbr,stdnt_name)
{
credHrs = credHrs1;
qualPts = qualPts1;
degSought = newDegree;
}
~Student();
//Functions for initializing the variables that will be output.
void setDegree(std:: string newDegree);
static double getGPA(unsigned int credHrs, unsigned int qualPts);
//The virtual functions are overwritten. Addclass allows for a change in GPA.
void addClass(unsigned int newClass, unsigned int newQualPts)
{
credHrs = credHrs + newClass;
qualPts = qualPts + newQualPts;
}
void display(void)
{
GPA = getGPA(credHrs, qualPts);
std::cout << "This student is active." << std::endl <<"ID #: "
<< idNbr << std::endl << "Name: " << name << std::endl
<< "GPA: " << GPA << std::endl << "Major: " << degSought
<< std::endl;
}
};
Student::~Student(){}
void Student::setDegree(std:: string newDegree)
{
degSought = newDegree;
}
//getGPA is declared and new students receive a 0
double Student::getGPA(unsigned int credHrs, unsigned int qualPts)
{
double GPA;
double credHrs1, qualPts1;
if (credHrs == 0)
{
GPA = 0;
}
else
{
credHrs1 = static_cast<double>(credHrs);
qualPts1 = static_cast<double>(qualPts);
GPA = qualPts1 / credHrs1;
}
return GPA;
}
#ifndef _Alumni
#define _Alumni
class Alumni : public ColMbr
{
private:
std::string degree;
int month, day, year;
public:
//An alumni constructor is defined.
Alumni(const unsigned int idNbr, std::string stdnt_name, int gradMonth, int gradDay, int gradYear, std::string newDegree) : ColMbr(idNbr, stdnt_name)
{
degree = newDegree;
month = gradMonth;
day = gradDay;
year = gradYear;
}
~Alumni();
//The virtual classes are overwritted.
//Even though addClass has no function here it is overwritten to ensure Alumni is not an abstract class.
void addClass(unsigned int credits, unsigned int gradePoint);
void display (void)
{
std::cout << "This student is an Alumni." << std::endl <<"ID #: "
<< idNbr << std::endl << "Name: " << name << std::endl
<< "Graduation Date: " << month << "/" << day << "/" << year
<< std::endl << "Major: " << degree << std::endl;
}
};
#endif
Alumni::~Alumni(){}
void Alumni::addClass(unsigned int credits, unsigned int gradePoint)
{}