C++实现Vector出现错误，哪位大佬看看怎么处理。

Question

我自定义一个MyVector，用来存储任意类型的对象，但我实现的时候出现以下错误，哪位大佬能帮帮我呀？一共三个文件：MyVector.h,MyVector.cpp和main.
cpp

1.MyVector.h

//
// Created by Howard on 2019/7/5.
//

#ifndef TEST_MYVECTOR_H
#define TEST_MYVECTOR_H

#endif //TEST_MYVECTOR_H

#include <iostream>

using namespace std;

template<typename T>
class MyVector {
    friend ostream &operator << <T> (ostream &out, const MyVector<T> &obj);   // 重载左移<< 右移>> 才将重载函数声明为友元函数
public:
    MyVector(int size = 0);   // 构造函数
    MyVector(const MyVector &obj);    // 拷贝构造函数
    ~MyVector();       // 析构函数

public:
    T &operator[](int index);

    MyVector &operator=(const MyVector &obj);


public:
    int getlen() {
        return m_len;
    }

protected:
    T *m_space;
    int m_len;
};

2.MyVector.cpp

//
// Created by Howard on 2019/7/5.
//

#include <iostream>

using namespace std;

#include "MyVector.h"


int size = 100;


// MyVector<int> myv1(10)
template<typename T>
MyVector<T>::MyVector(int size)   // 构造函数
{
    m_space = new T[size];
    m_len = size;
}


// MyVector<int> myv2 = myv1
template<typename T>
MyVector<T>::MyVector(const MyVector &obj)    // 拷贝构造函数
{
    // 根据myv1的大小分配内存
    m_len = obj.m_len;
    m_space = new T[size];
    // cpy数据
    for (int i = 0; i < m_len; i++) {
        m_space[i] = obj[i];
    }
}

template<typename T>
MyVector<T>::~MyVector()         // 析构函数
{
    if (m_space != NULL) {
        delete[] m_space;
        m_space = NULL;
        m_len = 0;
    }
}

template<typename T>
T &MyVector<T>::operator[](int index) {
    return m_space[index];
}

template<typename T>
MyVector<T> &MyVector<T>::operator=(const MyVector<T> &obj) {
    // 先把a2旧的内存释放掉
    if (m_space != NULL) {
        delete[] m_space;
        m_space = NULL;
        m_len = 0;
    }

    // 根据a1分配内存
    m_len = obj.m_len;
    m_space = new T[size];

    // cpy数据
    for (int i = 0; i < obj.m_len; i++) {
        m_space[i] = obj.m_space[i];
    }
    return *this;    // a2 = a1 返回给a2的自身


}


template<typename T>
ostream &operator<< <T>(ostream &out, const MyVector<T> &obj) {
    for (int i = 0; i < obj.m_len; i++) {
        out << obj.m_space[i] << " ";
    }
    // out << endl;
    return out;
}

3.main.cpp

#include <iostream>

using namespace std;

#include "MyVector.cpp"

int main() {
    MyVector<int> myv1(10);
    for (int i = 0; i < myv1.getlen(); i++) {
        myv1[i] = i + 1;
        cout << myv1[i] << " ";
    }
    cout << endl;

    MyVector<int> myv2 = myv1;
    for (int i = 0; i < myv2.getlen(); i++) {
        cout << myv2[i] << " ";
    }

    cout << myv2 << endl;


    system("pause");
    return 0;
}

运行结果：
In file included from F:\code\c++\test\main.cpp:5:
F:\code\c++\test\MyVector.cpp:76:61: error: non-class, non-variable partial specialization 'operator<< ' is not allowed
ostream &operator<< (ostream &out, const MyVector &obj) {
^
F:\code\c++\test\MyVector.cpp:76:61: error: non-class, non-variable partial specialization 'operator<< ' is not allowed
ostream &operator<< (ostream &out, const MyVector &obj) {
^
In file included from F:\code\c++\test\MyVector.cpp:9,
from F:\code\c++\test\main.cpp:5:
F:\code\c++\test\MyVector.h: In instantiation of 'class MyVector':
F:\code\c++\test\main.cpp:8:23: required from here
F:\code\c++\test\MyVector.h:16:21: error: template-id 'operator<< ' for 'std::ostream& operator<<(std::ostream&, const MyVector&)' does not match any template declaration
friend ostream &operator << (ostream &out, const MyVector &obj); // 閲嶈浇宸︾Щ<< 鍙崇Щ>> 鎵嶅皢閲嶈浇鍑芥暟澹版槑涓哄弸鍏冨嚱鏁�
^~~~~~~~~~~~~~~
In file included from D:/PROGRA~1/JETBRA~1/X86_64~1.0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/iostream:39,
from F:\code\c++\test\main.cpp:1:
D:/PROGRA~1/JETBRA~1/X86_64~1.0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/ostream:682:5: note: candidates are: 'template typename std::enable_ifstd::__and_<std::__not_<std::is_lvalue_reference<_Tp >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable::__ostream_type, const Tp&, void> >::value, typename std::_is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&)'
operator<<(_Ostream&& __os, const _Tp& __x)
^~~~~~~~

谁能告诉我，我哪个地方写错了？

Answer 1

 friend ostream &operator << <T> (ostream &out, const MyVector<T> &obj); 

为什么函数定义这里要加个 < T>

另外.h头文件中又定义了int size，后面的size都出现歧义了，没懂你想做什么