Thread: "error LNK2001: unresolved external symbol"problem

Code:

compile is OK,but something wrong with link,I don't know what the matter. Help!
The code  as  follows:


//stack.h
#include<iostream.h>
template<class TYPE>
class stack
{public:
stack(int s=10);
~stack()
{delete [] stackptr;
}
int push(const TYPE&);
int pop(TYPE&);
int isFull() const
{return top==size-1;
}
int isEmpty() const
{return top==-1;
}
private:
       int size;
       int top;
       TYPE* stackptr;
};


//stack.cpp
#include<iostream.h>
#include"stack.h"
template<class TYPE>
stack<TYPE>::stack(int s)
{size=s>0&&s<1000?s:10;
  top=-1;
  stackptr=new TYPE[size];
}

template<class TYPE>
int stack<TYPE>::push(const TYPE& item)
{if(!isFull())
{stackptr[++top]=item;
return 1;
}
return 0;
}

template<class TYPE>
int stack<TYPE>::pop(TYPE& popvalue)
{if(!isEmpty())
{popvalue=stackptr[top--];
return 1;
}
return 0;
}


//main.cpp
#include<iostream.h>
#include"stack.h"
int main()
{stack<char> charstack;
char c='a';
cout<<"pushing elements onto charstack"<<endl;
while(charstack.push(c))
{cout<<c<<" ";
c+=1;
}
cout<<endl<<"stack is full.cannot push"<<c<<endl<<"poping elements from charstack"<<endl;
while(charstack.pop(c))
cout<<c<<" ";
cout<<endl<<"stack is empty.cannot pop"<<endl;

stack<float> floatstack(5);
float f=1.1f;
cout<<"pushing elements onto floatstack"<<endl;
while(floatstack.push(f))
{cout<<f<<" ";
f+=1.1f;
}
cout<<endl<<"stack is full.cannot push"<<f<<endl<<"poping elements from floatstack"<<endl;
while(floatstack.pop(f))
cout<<f<<" ";
cout<<endl<<"stack is empty.cannot pop"<<endl;

stack<int> intstack;
int i=1;
cout<<"pushing elements onto intstack"<<endl;
while(intstack.push(i))
{cout<<i<<" ";
i+=1;
}
cout<<endl<<"stack is full.cannot push"<<i<<endl<<"poping elements from intstack"<<endl;
while(intstack.pop(i))
cout<<i<<" ";
cout<<endl<<"stack is empty.cannot pop"<<endl;
return 0;
}


-------------------Configuration: aaa - Win32 Debug--------------------
Compiling...
stack.cpp
main.cpp
Linking...
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<int>::pop(int &)" (?pop@?$stack@H@@QAEHAAH@Z)
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<int>::push(int const &)" (?push@?$stack@H@@QAEHABH@Z)
main.obj : error LNK2001: unresolved external symbol "public: __thiscall stack<int>::stack<int>(int)" (??0?$stack@H@@QAE@H@Z)
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<float>::pop(float &)" (?pop@?$stack@M@@QAEHAAM@Z)
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<float>::push(float const &)" (?push@?$stack@M@@QAEHABM@Z)
main.obj : error LNK2001: unresolved external symbol "public: __thiscall stack<float>::stack<float>(int)" (??0?$stack@M@@QAE@H@Z)
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<char>::pop(char &)" (?pop@?$stack@D@@QAEHAAD@Z)
main.obj : error LNK2001: unresolved external symbol "public: int __thiscall stack<char>::push(char const &)" (?push@?$stack@D@@QAEHABD@Z)
main.obj : error LNK2001: unresolved external symbol "public: __thiscall stack<char>::stack<char>(int)" (??0?$stack@D@@QAE@H@Z)
Debug/aaa.exe : fatal error LNK1120: 9 unresolved externals
执行 link.exe 时出错.

aaa.exe - 1 error(s), 0 warning(s)

Hello,

That's a common problem . You've created the definition and implementation of the template in separate files, which is something C++ compilers barely tolerate. Put the implementation of the template together with the declaration in the header file; it should compile then.