Matrix模板類通過const引用傳遞參數
[英]Matrix Template Class passing parameter by const reference
問題描述
試圖為矩陣對象編寫模板類。 編譯錯誤：
c：\\ program files（x86）\\ microsoft visual studio 11.0 \\ _vc \\ include \\ xmemory0（606）：錯誤C2558：類'Matrix'：沒有可用的復制構造函數或復制構造函數被聲明為'explicit'1> with 1> [1 > T = float 1>] 1> c：\\ program files（x86）\\ microsoft visual studio 11.0 \\ vc \\ include \\ xmemory0（605）：同時編譯類模板成員函數'void std :: allocator <_Ty> :: construct （_Ty *，const _Ty＆）'1>
1> [1> _Ty = Matrix 1>] 1> c：\\ program files（x86）\\ microsoft visual studio 11.0 \\ vc \\ include \\ xmemory0（751）：參見函數模板實例化'void std :: allocator < _Ty> :: construct（_Ty *，const _Ty＆）'正在編譯1> 1> [1>
_Ty = Matrix 1>] 1> c：\\ program files（x86）\\ microsoft visual studio 11.0 \\ vc \\ include \\ type_traits（743）：參見類模板實例化'std :: allocator <_Ty>'正在編譯1>用1> [1>
_Ty = Matrix 1>] 1> c：\\ program files（x86）\\ microsoft visual studio 11.0 \\ vc \\ include \\ vector（655）：參見類模板實例化'std :: is_empty <_Ty>'正在編譯1>用1> [1>
_Ty = std :: allocator> 1>] 1> e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ source.cpp（35）：請參閱類模板實例化'std :: vector <_Ty>'的引用編譯1> 1> [1>
_Ty = Matrix 1>] 1> 1>構建失敗。 1>
和
ClCompile：1> Source.cpp 1> e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ matrix.h（80）：error C2664：'Matrix :: Matrix（Matrix＆）'：無法轉換參數1 'Matrix（__ cdecl *）（void）'到'Matrix＆'1>
1> [1> T = float 1>] 1>
e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ matrix.h（74）：編譯類模板成員函數'Matrix Matrix :: dot（const Matrix＆）'1> with 1> [1>
T = float 1>] 1>
e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ source.cpp（62）：參見函數模板實例化'Matrix Matrix :: dot（const Matrix＆）'正在編譯1> 1> [1> T = float 1>] 1>
e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ source.cpp（38）：參見類模板實例化'Matrix'正在編譯1> 1> [1> T = float 1>
] 1> e：\\ projects \\ work \\ nns \\ fifteenstepstut \\ fifteensteps \\ fifteensteps \\ matrix.h（84）：錯誤C2664：'Matrix :: Matrix（Matrix＆）'：無法從'Matrix（__cdecl *）轉換參數1 （void）'to'Matrix＆'1>
1> [1> T = float 1>] 1> 1> Build FAILED。
“Matrix.h”
#include <vector>
#include <iostream>
template<typename T>
class Matrix {
private:
std::vector<T> data;
int rows;
int cols;
public:
Matrix();
Matrix(std::vector<T>, int rows, int cols);
Matrix(Matrix<T>&); //change with this one
//Matrix(const Matrix<T>&); //Will need to uncomment to test the 3rd error
void print();
Matrix<T> transpose();
Matrix<T> dot(const Matrix<typename std::remove_reference<T>::type> &); //error 2
//Matrix<T&> dot(const Matrix<T> &); //dumb idea?
//Matrix<T> dot(const Matrix<T> &); //error 1
};
template <typename T>
Matrix<T>::Matrix() {
data.clear();
rows = 0;
cols = 0;
}
template <typename T>
Matrix<T>::Matrix(std::vector<T> elements, int numRows, int numCols) {
rows = numRows;
cols = numCols;
data.clear();
for(unsigned int i = 0; i < elements.size(); i++) {
data.push_back(elements[i]);
}
}
template <typename T>
Matrix<T>::Matrix(Matrix<T>& matrix) {
rows = matrix.rows;
cols = matrix.cols;
data.clear();
for(unsigned int i = 0; i < matrix.data.size(); i++) {
data.push_back(matrix.data[i]);
}
}
/* To get compiler error, exchange with a above
template <typename T>
Matrix<T>::Matrix(const Matrix<T>& matrix) {
rows = matrix.rows;
cols = matrix.cols;
data.clear();
for(unsigned int i = 0; i < matrix.data.size(); i++) {
data.push_back(matrix.data[i]);
}
}*/
template <typename T>
Matrix<T> Matrix<T>::dot(const Matrix<typename std::remove_reference<T>::type> & rhs) { //ERROR 2
//Matrix<&T> dot(const Matrix<T> &) {
//Matrix<T> dot(const Matrix<T> &) { ERROR 1
if(cols != rhs.rows) {
std::cout << "Error! Can not resolve dot product on these matrices!" << std::endl;
std::cout << "Requested: [" << rows << "x" << cols << "] <alt+7> [" << rhs.rows << "x" << rhs.cols << "]" << std::endl;
Matrix<T> matrix();
return matrix;
}
Matrix<T> matrix();
return matrix;
}
template <typename T>
void Matrix<T>::print() {
for(unsigned int i = 0; i < data.size(); i++) {
std::cout << data[i] << ", ";
if((i+1) % cols == 0)
std::cout << std::endl;
}
}
template <typename T>
Matrix<T> Matrix<T>::transpose() {
std::vector<T> vec;
for(unsigned int i = 0; i < data.size(); i++) {
vec.push_back(data[(cols*(i%rows)+i/rows)]);
}
return Matrix<T>(vec, cols, rows);
}
我已經閱讀了幾個關於如何糾正這個問題的不同想法，但不確定問題是什么。 很多地方都在談論將T作為const引用傳遞，但在這種情況下，我將該類作為const引用傳遞。 似乎不喜歡那樣。
我終於決定看看如果實現一個const引用復制構造函數會發生什么。
然后我得到這個錯誤：
未解決的外部符號“public：class Matrix __thiscall Matrix :: dot（class Matrix const＆）”（？dot @？$ Matrix @ M @@ QAE？AV1 @ ABV1 @@ Z）在函數“void __cdecl testMatrixClass（void）”中引用“（？testMatrixClass @@ YAXXZ）
如果可能的話，我怎么能完成將這個類作為const引用傳遞？
謝謝！
測試實施
SOURCE.CPP
#include <iostream>
#include <vector>
#include "Matrix.h"
#include <string>
#include <fstream>
#include <sstream>
////TODO: Find alternatives to these...
//typedef std::vector<std::vector<float>> Matrix;
//typedef std::vector<float> Vector;
//using LMath::operator+;
//using LMath::operator==;
//void testMatrix(); //testing function.
//Matrix loadData(std::string); //Not implemented yet
//bool saveData(Matrix, std::string); //Not implemented yet
void testMatrixClass();
int main() {
//testMatrix();
testMatrixClass();
return 0;
}
void testMatrixClass() {
std::vector<Matrix<float>> testResults;
std::vector<std::string> testInfo;
Matrix<float> temp;
testResults.push_back(temp);
testInfo.push_back("Default Constructor");
std::vector<float> tempVec;
for(int i = 0; i < 9; i++) {
tempVec.push_back((float)(i%3));
}
Matrix<float> temp2(tempVec, 3, 3);
testResults.push_back(temp2);
testInfo.push_back("Vector constructor");
testResults.push_back(temp2.transpose());
testInfo.push_back("Vector transpose");
tempVec.push_back(10.0);
Matrix<float> temp3(tempVec, 5, 2);
testResults.push_back(temp3);
testInfo.push_back("Vector constructor");
testResults.push_back(temp3.transpose());
testInfo.push_back("Vector transpose");
testResults.push_back(temp2.dot(temp2));
testInfo.push_back("Dot product");
testResults.push_back(temp2.dot(temp3));
testInfo.push_back("Error Dot Product");
for(unsigned int i = 0; i < testResults.size(); i++) {
std::cout << "Test: " << testInfo[i] << ": " << std::endl;;
testResults[i].print();
std::cout << std::endl;
}
}
解：
#include <iostream>
#include <vector>
template<typename T>
class Matrix {
private:
std::vector<T> data;
int rows;
int cols;
public:
Matrix();
Matrix(std::vector<T>, int rows, int cols);
//Matrix(Matrix<T>&);
Matrix(const Matrix<T>&);
void print();
Matrix<T> transpose();
Matrix<T> dot(const Matrix<typename std::remove_reference<T>::type> &);
};
template <typename T>
Matrix<T>::Matrix() {
data.clear();
rows = 0;
cols = 0;
}
template <typename T>
Matrix<T>::Matrix(std::vector<T> elements, int numRows, int numCols) {
rows = numRows;
cols = numCols;
data.clear();
for(unsigned int i = 0; i < elements.size(); i++) {
data.push_back(elements[i]);
}
}
template <typename T>
Matrix<T>::Matrix(const Matrix<T>& matrix) {
rows = matrix.rows;
cols = matrix.cols;
data.clear();
for(unsigned int i = 0; i < matrix.data.size(); i++) {
data.push_back(matrix.data[i]);
}
}
template <typename T>
void Matrix<T>::print() {
for(unsigned int i = 0; i < data.size(); i++) {
std::cout << data[i] << ", ";
if((i+1) % cols == 0)
std::cout << std::endl;
}
}
template <typename T>
Matrix<T> Matrix<T>::transpose() {
std::vector<T> vec;
for(unsigned int i = 0; i < data.size(); i++) {
vec.push_back(data[(cols*(i%rows)+i/rows)]);
}
return Matrix<T>(vec, cols, rows);
}
template <typename T>
Matrix<T> Matrix<T>::dot(const Matrix<typename std::remove_reference<T>::type> & rhs) {
if(cols != rhs.rows) {
std::cout << "Error! Can not resolve dot product on these matrices!" << std::endl;
std::cout << "Requested: [" << rows << "x" << cols << "] <alt+7> [" << rhs.rows << "x" << rhs.cols << "]" << std::endl;
Matrix<T> matrix;
return matrix;
}
Matrix<T> matrix;
return matrix;
}
1 個解決方案
解決方案1
3 已采納 2018-10-27 00:37:26
將const引用作為函數參數傳遞給類成員函數
[英]Passing a const reference as a function parameter in a class member function
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