這段代碼爲什麼會引發LNK2019錯誤？

我只是確保通過構建這個簡單的程序來理解繼承，這個程序是Dog繼承了哺乳動物。編譯時出現錯誤。所有它應該做的是進入一個哺乳動物和狗的構造函數，樹皮，然後進入哺乳動物和狗的析構函數。我很抱歉縮進在帖子中出現了一點，它在Visual Studio中組織良好。這段代碼爲什麼會引發LNK2019錯誤？

#include <iostream> 
#include <string> 
using namespace std; 
class Mammal 
{ 
public: 
    Mammal(); 
    Mammal(int age); 
    Mammal(int age, int mammal); 
    ~Mammal(); 
    int getAge() {return itsAge;}; 
    int getWeight() {return itsWeight;}; 
    void setAge(int x) {itsAge = x;}; 
    void setWeight(int x) {itsWeight = x;}; 
    void speak() {cout << "MAMMALALALALALLLL!" << endl;}; 

private: 
    int itsAge, itsWeight; 
}; 

class Dog : public Mammal 
{ 
    public: 
     Dog(); 
     Dog(int age); 
     Dog(int age, int weight); 
     Dog(int age, int weight, string breed); 
     ~Dog(); 
     void setBreed(string breed) {itsBreed = breed;}; 
     string getBreed() {return itsBreed;}; 
     void bark() {cout << "Bark!" << endl;}; 
    private: 
     string itsBreed; 
}; 

Mammal::Mammal() 
{ 
    cout << "Mammal constructor." << endl; 
    setAge(0); 
    setWeight(0); 
} 

Mammal::Mammal(int age) 
{ 
    cout << "Mammel(int) constructor." << endl; 
    setAge(age); 
    setWeight(0); 
} 

Mammal::Mammal(int age, int weight) 
{ 
    cout << "Mammal(int, int) constructor." << endl; 
    setAge(age); 
    setWeight(weight); 
} 

Mammal::~Mammal() 
{ 
    cout << "Mammal deconstructor." << endl; 
} 

Dog::Dog(): 
Mammal() 
{ 
    cout << "Dog constructor." << endl; 
    setBreed(""); 
} 

Dog::Dog(int age): 
Mammal(age) 
{ 
    cout << "Dog(int) constructor." << endl; 
    setBreed(""); 
} 

Dog::Dog(int age, int weight): 
Mammal(age, weight) 
{ 
    cout << "Dog(int, int) constructor." << endl; 
    setBreed(""); 
} 

Dog::Dog(int age, int weight, string breed): 
Mammal(age, weight) 
{ 
    cout << "Dog(int, int, string) constructor." << endl; 
    setBreed(breed); 
} 


int main() 
{ 
    Dog Goldie(5, 50, "Lab"); 
    Goldie.bark(); 
    system("PAUSE"); 
    return 0; 
}

編譯器的輸出如下：

1>ClCompile: 
1> main.cpp 
1>main.obj : error LNK2019: unresolved external symbol "public: __thiscall Dog::~Dog(void)" ([email protected]@[email protected]) referenced in function _main 
1>c:\users\austin\documents\visual studio 2010\Projects\Inheritance\Debug\Inheritance.exe : fatal error LNK1120: 1 unresolved externals 
1> 
1>Build FAILED. 
1> 
1>Time Elapsed 00:00:00.31 
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

來源

2011-11-22 SaxSalute

請張貼完整的錯誤消息你得到。 –

也許你可以發佈它給你的錯誤;）？ – Smash

剛剛發佈了來自編譯器的完整日誌，對此抱歉。 – SaxSalute

您申報Dog類的析構函數，但沒有定義它。
你應該定義它。

Dog::~Dog(){}

錯誤的GCC，清楚地告訴說：

prog.cpp :(文字+ 0xf54）：未定義的參考狗::〜狗（）
prog.cpp :(。文字+ 0xfc3）：未定義的引用狗::〜狗（）

Working sample代碼的修改後

來源

2011-11-22 15:36:52

您還沒有定義的析構函數Dog：

Dog::~Dog() 
{ 
    cout << "Dog destructor." << endl; 
}

來源

2011-11-22 15:36:57 razlebe

這段代碼爲什麼會引發LNK2019錯誤？

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