[英]C++ I/O stream overload: How to implement friend overload, for 3 different classes, of the same 4 i/o functions in the same header?
我有一個簡單的OpenGL項目。 它的結構非常簡單:
Figure.h(位於下方)-> TFigureMatrix.h(用於操作圖形的模板)-> Cluster.h(類似於用於組織所有主要功能的子菜單)-> Source.cpp(控制台菜單)
圖.h:
#pragma once
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <vector>
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <time.h>
#include <iomanip>
#define RND1 (GLfloat)((rand() % 101)/500.)
#define RND2 (GLfloat)((rand() % 151-75)/100.)
#define RND3 (GLfloat)(rand() % 361)
#define SQR(x) ((x)*(x))
#define Len2(i, j) sqrt(SQR(Fig[i*3] - Fig[j*3]) + SQR(Fig[1+i*3] - Fig[1+j*3]))
#define MIN_val 0.005
class Square
{
GLfloat Fig[18] = {
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f
};
public:
inline GLfloat S() { return SQR(Fig[3]); };
inline GLfloat P() { return Fig[3] * 4; };
inline GLfloat D() {
return sqrt(
SQR((Fig[0] + Fig[3] + Fig[6] + Fig[9]) / 4. + Fig[12]) +
SQR((Fig[1] + Fig[4] + Fig[7] + Fig[10]) / 4. + Fig[13]) +
SQR((Fig[2] + Fig[5] + Fig[8] + Fig[11]) / 4. + Fig[14]));
};
inline GLfloat* GetFig() { return Fig; };
void Rnd() {
memset(Fig, 0, sizeof(Fig));
Fig[3] = RND1;
Fig[12] = RND2; Fig[13] = RND2; Fig[14] = RND2;
Fig[15] = RND3; Fig[16] = RND3; Fig[17] = RND3;
Fig[7] = Fig[3]; Fig[9] = Fig[3]; Fig[10] = Fig[3];;
};
friend std::istream &operator >> (std::istream &, Square &);
friend std::ostream &operator << (std::ostream &, Square &);
friend std::ifstream &operator >> (std::ifstream &, Square &);
friend std::ofstream &operator << (std::ofstream &, Square &);
};
class Rectang
{
GLfloat Fig[18] = {
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f
};
public:
inline GLfloat S() { return Fig[3] * Fig[7]; };
inline GLfloat P() { return (Fig[3] + Fig[7]) * 2; };
inline GLfloat D() {
return sqrt(
SQR((Fig[0] + Fig[3] + Fig[6] + Fig[9]) / 4. + Fig[12]) +
SQR((Fig[1] + Fig[4] + Fig[7] + Fig[10]) / 4. + Fig[13]) +
SQR((Fig[2] + Fig[5] + Fig[8] + Fig[11]) / 4. + Fig[14]));
};
inline GLfloat* GetFig() { return Fig; };
void Rnd() {
memset(Fig, 0, sizeof(Fig));
Fig[3] = RND1; Fig[7] = RND1;
Fig[12] = RND2; Fig[13] = RND2; Fig[14] = RND2;
Fig[15] = RND3; Fig[16] = RND3; Fig[17] = RND3;
Fig[9] = Fig[3]; Fig[10] = Fig[7];
};
friend std::istream &operator >> (std::istream &, Rectang &);
friend std::ostream &operator << (std::ostream &, Rectang &);
friend std::ifstream &operator >> (std::ifstream &, Rectang &);
friend std::ofstream &operator << (std::ofstream &, Rectang &);
};
class Triangle
{
GLfloat Fig[15] = {
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f,
0.0f,0.0f,0.0f
};
public:
inline GLfloat P() { return Len2(0, 1) + Len2(0, 2) + Len2(1, 2); };
inline GLfloat S() { GLfloat hP = P() / 2.0f; return sqrt(hP*(hP - Len2(0, 1))*(hP - Len2(0, 2))*(hP - Len2(1, 2))); };
inline GLfloat D() {
return sqrt(
SQR((Fig[0] + Fig[3] + Fig[6]) / 3. + Fig[9]) +
SQR((Fig[1] + Fig[4] + Fig[7]) / 3. + Fig[10]) +
SQR((Fig[2] + Fig[5] + Fig[8]) / 3. + Fig[11]));
};
inline GLfloat* GetFig() { return Fig; };
void Rnd() {
memset(Fig, 0, sizeof(Fig));
Fig[3] = RND1; Fig[6] = RND1; Fig[7] = RND1;
Fig[9] = RND2; Fig[10] = RND2; Fig[11] = RND2;
Fig[12] = RND3; Fig[13] = RND3; Fig[14] = RND3;
};
friend std::istream &operator >> (std::istream &, Triangle &);
friend std::ostream &operator << (std::ostream &, Triangle &);
friend std::ifstream &operator >> (std::ifstream &, Triangle &);
friend std::ofstream &operator << (std::ofstream &, Triangle &);
};
std::istream &operator >> (std::istream &stream, Square &obj) {
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >> obj.Fig[3] >> obj.Fig[7] >> obj.Fig[9] >> obj.Fig[10]
>> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14]
>> obj.Fig[15] >> obj.Fig[16] >> obj.Fig[17];
return stream;
};
std::ostream &operator << (std::ostream &stream, Square &obj) {
stream << "\n/(x: " << obj.Fig[3] << ")";
return stream;
};
std::ifstream &operator >> (std::ifstream &stream, Square &obj) {
char delim;
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >>
delim >> obj.Fig[3] >>
delim >> obj.Fig[7] >>
delim >> obj.Fig[9] >>
delim >> obj.Fig[10] >>
delim >> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14] >>
delim >> obj.Fig[15] >> obj.Fig[16] >> obj.Fig[17];
return stream;
};
std::ofstream &operator << (std::ofstream &stream, Square &obj) {
stream << "\n" << std::fixed << std::setprecision(3)
<< "\nx " << obj.Fig[3] << "\ny " << obj.Fig[7]
<< "\nx " << obj.Fig[9] << "\ny " << obj.Fig[10] << std::setprecision(2)
<< "\nm " << obj.Fig[12] << " " << obj.Fig[13] << " " << obj.Fig[14]
<< "\nr " << obj.Fig[15] << " " << obj.Fig[16] << " " << obj.Fig[17];
return stream;
};
std::istream &operator >> (std::istream &stream, Rectang &obj) {
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >> obj.Fig[3] >> obj.Fig[7] >> obj.Fig[9] >> obj.Fig[10]
>> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14]
>> obj.Fig[15] >> obj.Fig[16] >> obj.Fig[17];
return stream;
};
std::ostream &operator << (std::ostream &stream, Rectang &obj) {
stream << "\n/(x: " << obj.Fig[3] << "|y: " << obj.Fig[7] << ")";
return stream;
};
std::ifstream &operator >> (std::ifstream &stream, Rectang &obj) {
char delim;
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >>
delim >> obj.Fig[3] >>
delim >> obj.Fig[7] >>
delim >> obj.Fig[9] >>
delim >> obj.Fig[10] >>
delim >> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14] >>
delim >> obj.Fig[15] >> obj.Fig[16] >> obj.Fig[17];
return stream;
};
std::ofstream &operator << (std::ofstream &stream, Rectang &obj) {
stream << "\n" << std::fixed << std::setprecision(3)
<< "\nx " << obj.Fig[3] << "\ny " << obj.Fig[7]
<< "\nx " << obj.Fig[9] << "\ny " << obj.Fig[10] << std::setprecision(2)
<< "\nm " << obj.Fig[12] << " " << obj.Fig[13] << " " << obj.Fig[14]
<< "\nr " << obj.Fig[15] << " " << obj.Fig[16] << " " << obj.Fig[17];
return stream;
};
std::istream &operator >> (std::istream &stream, Triangle &obj) {
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >> obj.Fig[3] >> obj.Fig[6] >> obj.Fig[7]
>> obj.Fig[9] >> obj.Fig[10] >> obj.Fig[11]
>> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14];
return stream;
};
std::ostream &operator << (std::ostream &stream, Triangle &obj) {
stream << "\n/(x: " << obj.Fig[3] << "|x: " << obj.Fig[6] << " y: " << obj.Fig[7] << ")";
return stream;
};
std::ifstream &operator >> (std::ifstream &stream, Triangle &obj) {
char delim;
memset((void*)obj.Fig, 0, sizeof(obj.Fig));
stream >>
delim >> obj.Fig[3] >>
delim >> obj.Fig[6] >>
delim >> obj.Fig[7] >>
delim >> obj.Fig[9] >> obj.Fig[10] >> obj.Fig[11] >>
delim >> obj.Fig[12] >> obj.Fig[13] >> obj.Fig[14];
return stream;
};
std::ofstream &operator << (std::ofstream &stream, Triangle &obj) {
stream << "\n" << std::fixed << std::setprecision(3)
<< "\nx " << obj.Fig[3] << "\nx " << obj.Fig[6]
<< "\ny " << obj.Fig[7] << std::setprecision(2)
<< "\nm " << obj.Fig[9] << " " << obj.Fig[10] << " " << obj.Fig[11]
<< "\nr " << obj.Fig[12] << " " << obj.Fig[13] << " " << obj.Fig[14];
return stream;
};
目的是將其包含在另一個模板類中,該類將在此處類似地處理所有不同的圖形。 問題是,似乎我無法在一個標頭中創建2個或更多類似的朋友重載:
std::istream &operator >> (std::istream &stream, Square &obj)
std::istream &operator >> (std::istream &stream, Rectang &obj)
例如,在Figure.h中,他指出了13個類似的錯誤,如下所示:
LNK2005 "class std::basic_ifstream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_ifstream<char,struct std::char_traits<char> > &,class Rectang &)" (??5@YAAAV?$basic_ifstream@DU?$char_traits@D@std@@@std@@AAV01@AAVRectang@@@Z) already defined in Cluster.obj
如果我將這些內容放到課程中,顯然不會看到它們,因為它們一定是朋友。 如果我在所有數字obj之前添加const,則“ >> / << const what_type”沒有重載。
我該如何解決? (很抱歉有任何錯誤,或者如果我的問題已經被提出,還沒有找到)
您正在標頭中定義函數。 這將在您包含該標頭的每個.cpp文件中定義函數。 鏈接器會看到所有這些功能,但不知道它們是作為同一功能使用的,因此會出錯。
添加內聯關鍵字作為快速點擊。
inline std::ofstream &operator << (std::ofstream &stream, Triangle &obj) {
...
}
或者在標頭中聲明函數,然后在單個.cpp文件中定義它們。
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