c++ - 为什么包含.h文件报错，包含.cpp文件却可以？！
头文件：XXX.h
#ifndef QUEUE_BUFFER_H_
#define QUEUE_BUFFER_H_
template<typename T>
struct Buffer
{
T _data;
int _BufNo;
Buffer *next;
Buffer(int No, T data): _data(data), _BufNo(No), next(NULL) {}
};
template<typename T>
class Buffer_Queue
{
private:
int _length; // 队列元素个数
Buffer<T> *front; // 队列的头指针
Buffer<T> *rear; // 队列的尾指针
bool isEmpty() const; // 判断队列是否为空
public:
Buffer_Queue(T data, int length = 10); // 构造函数
~Buffer_Queue();
Buffer<T> *getbuf(); // 获得空的buffer(出队)
void putbuf(Buffer<T> *buf); // 挂载到队尾(入队)
void display(); // 测试输出
};
#endif定义：XXX.cpp
#include <cstdlib>
#include <iostream>
#include "queue_buffer.h"
using std::cout;
using std::endl;
using std::cerr;
template<typename T>
Buffer_Queue<T>::Buffer_Queue(T data, int length): _length(length) // 构造函数
{
front = rear = NULL;
int i = 0;
if (i < _length)
{
// 分配第一个结点
Buffer<T> *p = new Buffer<T>(i++, data);
if (!p)
{
cerr << "Memory alloc failed" << endl;
exit(1);
}
front = rear = p;
front->next = NULL; // 多余
}
while (i < _length)
{
Buffer<T> *p = new Buffer<T>(i++, data);
if (!p)
{
cerr << "Memory alloc failed" << endl;
exit(1);
}
rear->next = p;
rear = p;
}
}
template<typename T>
bool Buffer_Queue<T>::isEmpty() const
{
return _length == 0;
}
template<typename T>
Buffer<T> * Buffer_Queue<T>::getbuf() // 出队
{
if (isEmpty()) // 如果队列为空，则返回NULL
return NULL;
Buffer<T> *p = front;
front = front->next;
_length--;
p->next = NULL;
if (rear == p) // 只有一个结点
rear = front;
return p;
}
template<typename T>
void Buffer_Queue<T>::putbuf(Buffer<T> *buf) // 入队
{
if (isEmpty()) // 如果队列为空
{
front = rear = buf;
front->next = NULL;
++_length;
}
// 队列不为空
rear->next = buf;
rear = buf;
rear->next = NULL;
++_length;
}
template<typename T>
void Buffer_Queue<T>::display()
{
Buffer<T> *curr = front;
while (curr)
{
cout << curr->_BufNo << ": " << curr->_data << endl;
curr = curr->next;
}
}
template<typename T>
Buffer_Queue<T>::~Buffer_Queue()
{
Buffer<T> *curr = NULL;
while (front)
{
curr = front;
front = front->next;
delete curr;
}
}测试：test.cpp
#include <iostream>
#include "queue_buffer.h"
int main(void)
{
Buffer_Queue<int> test(-1); // 10个
test.display();
Buffer<int> *p = new Buffer<int>(10, -1);
test.putbuf(p);
Buffer_Queue<int> temp(-1, 0); // 0个
temp.putbuf(p);
test.display();
temp.display();
return 0;
}编译： g++ xxx.cpp test.cpp -o test
test.cpp文件中包含xxx.h就报错，undefined reference to XXXXXXXX（是调用的那些函数）
test.cpp文件中包含xxx.cpp就不会报错，一切正常
