failed to compile C++ when using #include .h file
I have 3 files: linkedStack.cpp linkedStack.h and main.cpp.
g++ -o main linkedStack.cpp main.cpp
it failed to compile when I enter the command above,
but it worked when I changed #include "linkedStack.h" into #include "linkedStack.cpp".
I wonder why?
The linkedStack.h file is as follows:
#include <stdio.h>
#include <iostream>
#include <string>
#include <assert.h>
using namespace std;
template <class Type>
class stackADT
{
public:
virtual void push(const Type& newItem)=0;//to add newItem to the stack
virtual Type top() const=0;//to return the top element of the stack
template <class Type>
struct nodeType
{
Type info;
nodeType<Type>*link;
};
template <class Type>
class linkedStackType//:public stackADT<Type>
{
public:
virtual void push(const Type& newItem);//add a new element
linkedStackType();//default constructor
~linkedStackType();//destructor
virtual Type top() const;//return the top element
private:
nodeType<Type>*stackTop;
};
The linkedStack.cpp file is as follows:
#include "linkedStack.h"
template <class Type>
linkedStackType<Type>::linkedStackType()
{//default constructor
stackTop=NULL;
}
template <class Type>
Type linkedStackType<Type>::top() const
{
assert(stackTop!=NULL);
return stackTop->info;
}//return the top element of the stack ,otherwise terminate the program if the stack is empty
template <class Type>
void linkedStackType<Type>::push(const Type& newItem)
{//add a new element
nodeType<Type>* newNode;
newNode =new nodeType<Type>;
newNode->info=newItem;
newNode->link=stackTop;
stackTop=newNode;
}
The main.cpp file is as follows:
#include <linkedStack.h>
int main()
{
linkedStackType<int> stack;
stack.push(34);
cout<<stack.top()<<endl;
return 0;
}
The result is as follows :
g++ -o main linkedStack.cpp main.cpp
Undefined symbols for architecture x86_64:
"linkedStackType<int>::isFullStack() const", referenced from:
vtable for linkedStackType<int> in main0728-bb04be.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
