Question

嗨，堆栈溢出的人，

我正在编程一个计算复数总和的程序，并在修复退出其他（编译）错误之后我遇到了链接器错误，我似乎无法解决。我几乎看不到它的用途，但在尝试了一些之后，看了上网并在退出一段时间后得到了同样的错误我决定在这里发布。

注意：“std_lib_facilities.h”是一个库，在我使用的书中使用，并添加了不同的库，如，等等。

这是我得到的链接器错误，我删除了长地址：

Severity    Code    Description Project File    Line    Suppression State
Error   LNK1120 3 unresolved externals  <adress> project.exe    1   
Error   LNK2019 unresolved external symbol "public: __thiscall Complex::Complex(void)" (??0Complex@@QAE@XZ) referenced in function "public: class Complex __thiscall Complex::Add(class Complex)" (?Add@Complex@@QAE?AV1@V1@@Z) <adress> Complex.obj    1   
Error   LNK2001 unresolved external symbol "public: __thiscall Complex::Complex(void)" (??0Complex@@QAE@XZ) <adress> Numbers.obj    1   
Error   LNK2019 unresolved external symbol "public: __thiscall Complex::~Complex(void)" (??1Complex@@QAE@XZ) referenced in function "public: class Complex __thiscall Complex::Add(class Complex)" (?Add@Complex@@QAE?AV1@V1@@Z)    <adress> Complex.obj    1   
Error   LNK2019 unresolved external symbol "public: __thiscall Complex::Complex(double,double)" (??0Complex@@QAE@NN@Z) referenced in function _main <adress> Numbers.obj    1

我很抱歉代码加载。是否可以下次将其上传到Github？

亲切的问候。

主程序：

#include "Complex.h"
#include "std_lib_facilities.h"

int main() {
    double a1 = 0; //First real number.
    double b1 = 0; //First imaginary.
    double a2 = 0; //Second real number.
    double b2 = 0; //Second imaginary.
    char choice;

    cout << "Please enter a number for the first real part:";
    cin >> a1;
    cout << "\nPlease enter a number for the first imaginary number:";
    cin >> b1;
    Complex complex1(a1, b1);
    complex1.print();

    cout << "Please enter a number for the first real part:";
    cin >> a2;
    cout << "\nPlease enter a number for the first imaginary number:";
    cin >> b2;
    Complex complex2(a2, b2);
    complex2.print();

    cout << "\nPlease choose or you want to add (+), subtract (-) or multiply (*) the two answers by entering the right character:";
    cin >> choice;

    Complex c;
    if (choice == '+') {
        c = complex1.Add(complex2);
        cout << "\nResult for addition is: (" << c.getReal() << ")+(" <<    c.getImag() << ")i\n";
}

    else if (choice == '-') {
        c = complex1.Sub(complex2);
        cout << "\nResult for subtraction is: (" << c.getReal() << ")+(" << c.getImag() << ")i\n";
}
    else if (choice == '*') {
        c = complex1.Mult(complex2);
        cout << "\nResult for multiplication is: (" << c.getReal() << ")+(" << c.getImag() << ")i\n";
}

    keep_window_open();

    return 0;
}

Complex.cpp

#include "Complex.h"
#include "std_lib_facilities.h"

void Complex::setA(double a) { //Bind attribute a to a.
    this->a = a;
}

void Complex::setB(double b) { //Bind attribute b to b.
    this->b = b;
}

void Complex::eaqualize(double r, double i) { //Eaqualize a and b to 0 and bind r and i to them.
        a = b = 0;
        a = r;
        b = i;
    }

void Complex::objects(Complex &complex) { //Define objects for a and b.
        a = complex.a;
        b = complex.b;
    }

Complex Complex::Add(Complex c) {
    Complex Add;
        Add.a = a + c.a;
        Add.b = b + c.b;
        return Add;
    }

Complex Complex::Sub(Complex c) {
    Complex Sub;
        Sub.a = a - c.a;
        Sub.b = b - c.b;
        return Sub;
    }

Complex Complex::Mult(Complex c) {
    Complex Mult;
        Mult.a = a * c.a - b * c.b;
        Mult.b = a * c.b - c.a*b;
        return Mult;
    }


void Complex::print() {
        cout << a << "+" << b << "i" << endl << endl;
    }

double Complex::getReal() const {
    return a;
}

double Complex::getImag() const {
    return b;
}

void Complex::setReal(double a, double re) {
    this->a = re;

}

void Complex::setImag(double b, double im) {
    this->b = im;
}

Complex.h

#ifndef _Complex
#define _Complex

class Complex {
    //Attributes
    double a; //Real input
    double b; //Imaginairy input
    double r; //Real converted
    double i; //Imaginairy converted
    double c;

public:
    Complex();
    Complex(double a, double b); //Constructor
    //Complex(double c); //Another constructor

    //Methode
    void setA(double a);
    void setB(double b);
    void eaqualize(double r, double i);
    void objects(Complex &complex);
    Complex Add(Complex c);
    Complex Sub(Complex c);
    Complex Mult(Complex c);
    void print();
    double getReal(void) const;
    double getImag(void) const;
    void setReal(double a, double re);
    void setImag(double b, double im);

    ~Complex(); //Destructor
#endif;
};

Answer 1

链接器消息相当清楚，不是吗？也许如果我删除一些装饰品？

未解决的外部符号＆＃34;复杂::复杂（无效）＆＃34;
  未解决的外部符号＆＃34;复杂::复杂（无效）＆＃34;
  未解决的外部符号＆＃34;复杂::〜复杂（无效）＆＃34;
  未解决的外部符号＆＃34;复杂::复杂（双，双）＆＃34;

您缺少Complex（已报告两次）的默认构造函数的定义，Complex的析构函数以及Complex的构造函数，其中两个double为参数。传统上，这些定义将与Complex.cpp的其他方法的定义一起出现在Complex中，除非它们足够简单，可以在头文件中提供内联定义。

根据您定义的方法，看起来您不倾向于内联定义。因此，请将Complex::Complex()，Complex::Complex(double,double)和Complex::~Complex()的定义添加到Complex.cpp。

Answer 2

好吧，我已经编辑了代码并使代码更短，但看来我仍然遇到一些链接器错误。回到JaMiT的问题：不，链接器错误对我来说不是很清楚。编译器错误更清晰，并且提供错误所在的行。例如，我没有得到的是我再次得到了析构函数的链接器错误。

Error   LNK2019 unresolved external symbol "public: __thiscall Complex::~Complex(void)" (??1Complex@@QAE@XZ) referenced in function "public: class Complex __thiscall Complex::operator*(class Complex const &)" (??DComplex@@QAE?AV0@ABV0@@Z <address on disk> Complex.obj 1

所以简而言之：LNK2019在Complex :: ~~ Complex（void）处未解析的外部符号

但是，如果我的class.cpp文件中已经存在我的header / .h文件中的析构函数，为什么还要重新声明呢？

不同的链接器错误

2 个答案: