我遇到运行此代码的问题。它应该是带有构造函数，析构函数，复制构造函数和运算符重载的模板化2D数组。
我的主要问题是导致错误的ostream& operator<<(ostream& os, SafeMatrix<class T> s)重载版。主要是，当我cout<<b[0][0]时，它打印得很好，但当我在ostream& operator<<(ostream& os, SafeMatrix<class T> s)上传器中执行时，我会收到错误。我正在尝试打印像cout << b这样的对象，正如您在main中看到的那样。
可能存在很多编码错误。对不起，我是模板和重载的新手。我一直在阅读和阅读，找不到与我的项目相关的任何内容。
#include <iostream>
#include <cstdlib>
#include <cassert>
using namespace std;
template <class T> class SafeMatrix{
private:
int row_low, row_high, col_low, col_high;
T** p;
public:
// default constructor
// allows for writing things like SafeMatrix a;
SafeMatrix() : row_low(0), row_high(-1)
, col_low(0), col_high(-1), p(nullptr){ }
// 1 parameter constructor
// SafeMatrix (10);
SafeMatrix(int dim){
if (dim <= 0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
row_low = 0; row_high = dim - 1;
col_low = 0; col_high = dim - 1;
p = new T*[dim];
for (int i = 0; i < dim; i++)
p[i] = new T[dim];
}
// 2 parameter constructor lets us write
// SafeMatrix (10,20);
SafeMatrix(int row, int col){
if (row <= 0 || col<=0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
row_low = 0; row_high = row - 1;
col_low = 0; col_high = col - 1;
p = new T*[row];
for (int i = 0; i < row; i++)
p[i] = new T[col];
}
// 2 parameter constructor lets us write
// SafeMatrix (10,20);
SafeMatrix(int row_low, int row_high, int col_low, int col_high){
if ((row_high - row_low + 1) <= 0 || (col_high - col_low + 1) <= 0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
this.row_low = row_low; this.row_high = row_high - 1;
this.col_low = col_low; this.col_high = col_high - 1;
p = new T*[(col_high - col_low) + 1];
for (int i = 0; i <= row_high-row_low; i++)
p[i] = new T[(col_high - col_low) + 1];
}
// copy constructor for pass by value and
// initialization
SafeMatrix(const SafeMatrix &s){
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
p = new T*[row];
for (int i = 0; i < row; i++)
p[i] = new T[col];
for (int i = 0; i < row; i++)
for (int j = 0; j < col;j++)
p[i][j] = s.p[i][j];
row_low = s.row_low; row_high = s.row_high;
col_low = s.col_low; col_high = s.col_high;
}
// destructor
~SafeMatrix(){
for (int i = 0; i < (row_high - row_low) + 1; i++)
delete[] p[i];
delete[] p;
}
friend class Brackets;
//overloaded [] lets us write
//SafeMatrix x(10,20); x[15]= 100;
class Brackets {
private:
T* p1;
public:
Brackets(T* p2) : p1(p2) { }
T& operator[](int i) {
/*if (i<col_low || i>col_high) {
cout << "index " << i << " out of range" << endl;
exit(1);
}*/
return p1[i];
}
};
Brackets operator[](int i) {
if (i<row_low || i>row_high) {
cout << "index " << i << " out of range" << endl;
system("pause");
exit(1);
}
return Brackets(p[i]);
}
// overloaded assignment lets us assign
// one SafeMatrix to another
SafeMatrix& operator=(const SafeMatrix & s){
if (this != &s){
delete[] p;
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
p = new T*[row];
for (int i = 0; i < col; i++)
p[i] = new T[col];
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
p[i][j] = s.p[i][j];
this.row_low = s.row_low; this.row_high = s.row_high;
this.col_low = s.col_low; this.col_high = s.col_high;
}
return *this;
}
// overloads << so we can directly print SafeMatrix
friend ostream& operator<<(ostream& os, const SafeMatrix<T> s);
};
ostream& operator<<(ostream& os, SafeMatrix<class T> s){
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
for (int i = 0; i < row; i++){
for (int j = 0; j < col; j++){
cout << *((s.p+i)+j) << " ";
}
cout << endl;
}
return os;
};
int main(){
SafeMatrix<int> b(3, 5);
b[2][0] = 3;
cout << b[2][0] <<endl;
int counter = 0;
for (int i = 0; i<3; i++)
for (int j = 0; j < 5; j++)
b[i][j] = ++counter;
cout << "printing b the first time" <<endl;
cout << b << endl;
cout << "printing using []" << endl;
for (int i = 0; i < 3; i++){
for (int j = 0; j < 5; j++){
cout << b[i][j] << " ";
}
cout << endl;
}
}
我得到的错误有点疯狂，但在这里它们是：
error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class SafeMatrix<int>)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@V?$SafeMatrix@H@@@Z) referenced in function _main D:\OneDrive\VS\SafeMatrix\matrix.obj SafeMatrix
和
error LNK1120: 1 unresolved externals D:\OneDrive\VS\SafeMatrix\Debug\SafeMatrix.exe 1 1 SafeMatrix
和这个警告：
Warning 1 warning C4150: deletion of pointer to incomplete type 'T'; no destructor called d:\onedrive\vs\safematrix\matrix.cpp 82 1 SafeMatrix
不知道这些是什么意思。
答案 0 :(得分：0)
重载的运算符声明必须是自己的模板声明：
template <class U>
ostream& operator<<(ostream& os, const SafeMatrix<U> s);
此外，类中的friend声明必须使用新的类型参数名称，如：
template <class U>
friend ostream& operator<<(ostream& os, const SafeMatrix<U> s);
它可能不会重用T类型参数。重载运算符的类型参数是另一个。
答案 1 :(得分：0)
我认为你很简单忘了添加模板来重载。我没有检查其余部分：
#include <iostream>
#include <cstdlib>
#include <cassert>
using namespace std;
template <typename T> class SafeMatrix{
private:
int row_low, row_high, col_low, col_high;
T** p;
public:
// default constructor
// allows for writing things like SafeMatrix a;
SafeMatrix() : row_low(0), row_high(-1)
, col_low(0), col_high(-1), p(nullptr){ }
// 1 parameter constructor
// SafeMatrix (10);
SafeMatrix(int dim){
if (dim <= 0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
row_low = 0; row_high = dim - 1;
col_low = 0; col_high = dim - 1;
p = new T*[dim];
for (int i = 0; i < dim; i++)
p[i] = new T[dim];
}
// 2 parameter constructor lets us write
// SafeMatrix (10,20);
SafeMatrix(int row, int col){
if (row <= 0 || col <= 0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
row_low = 0; row_high = row - 1;
col_low = 0; col_high = col - 1;
p = new T*[row];
for (int i = 0; i < row; i++)
p[i] = new T[col];
}
// 2 parameter constructor lets us write
// SafeMatrix (10,20);
SafeMatrix(int row_low, int row_high, int col_low, int col_high){
if ((row_high - row_low + 1) <= 0 || (col_high - col_low + 1) <= 0){
cout << "constructor error in bounds definition" << endl;
exit(1);
}
this.row_low = row_low; this.row_high = row_high - 1;
this.col_low = col_low; this.col_high = col_high - 1;
p = new T*[(col_high - col_low) + 1];
for (int i = 0; i <= row_high - row_low; i++)
p[i] = new T[(col_high - col_low) + 1];
}
// copy constructor for pass by value and
// initialization
SafeMatrix(const SafeMatrix &s){
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
p = new T*[row];
for (int i = 0; i < row; i++)
p[i] = new T[col];
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
p[i][j] = s.p[i][j];
row_low = s.row_low; row_high = s.row_high;
col_low = s.col_low; col_high = s.col_high;
}
// destructor
~SafeMatrix(){
for (int i = 0; i < (row_high - row_low) + 1; i++)
delete[] p[i];
delete[] p;
}
friend class Brackets;
//overloaded [] lets us write
//SafeMatrix x(10,20); x[15]= 100;
class Brackets {
private:
T* p1;
public:
Brackets(T* p2) : p1(p2) { }
T& operator[](int i) {
/*if (i<col_low || i>col_high) {
cout << "index " << i << " out of range" << endl;
exit(1);
}*/
return p1[i];
}
};
Brackets operator[](int i) {
if (i<row_low || i>row_high) {
cout << "index " << i << " out of range" << endl;
system("pause");
exit(1);
}
return Brackets(p[i]);
}
// overloaded assignment lets us assign
// one SafeMatrix to another
SafeMatrix& operator=(const SafeMatrix & s){
if (this != &s){
delete[] p;
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
p = new T*[row];
for (int i = 0; i < col; i++)
p[i] = new T[col];
for (int i = 0; i < row; i++)
for (int j = 0; j < col; j++)
p[i][j] = s.p[i][j];
this.row_low = s.row_low; this.row_high = s.row_high;
this.col_low = s.col_low; this.col_high = s.col_high;
}
return *this;
}
// overloads << so we can directly print SafeMatrix
template <typename T> friend ostream& operator<<(ostream& os, const SafeMatrix<T> s);
};
template <typename T>
ostream& operator<< (ostream& os, const SafeMatrix<T> s) {
int row = (s.row_high - s.row_low) + 1,
col = (s.col_high - s.col_low) + 1;
for (int i = 0; i < row; i++){
for (int j = 0; j < col; j++){
os << *((s.p + i) + j) << " ";
}
os << endl;
}
return os;
}
int main(){
SafeMatrix<int> a(10), b(3, 5);
b[2][0] = 3;
cout << b << endl;
system("PAUSE");
return 0;
}
此代码适用于十六进制打印...