6.再谈重载：一个矢量类
位移矢量指的是从何处开始到何处结束，而不是经过的路线。
VECTOR.h
#pragma once #ifndef VECTOR_H__ #define VECTOR_H__ #include <iostream> using namespace std; namespace Vector { class VECTOR1 { public: enum Mode { RECT, POL }; private: double x; // horizontal value double y; // vertical value double mag; // length of vector double ang; // direction of vector in degrees Mode mode; // RECT or POL // private methods for setting values void set_mag(); void set_ang(); void set_x(); void set_y(); public: VECTOR1(); VECTOR1(double n1, double n2, Mode form = RECT); void reset(double n1, double n2, Mode form = RECT); double xval() const { return x; } // report x value double yval() const { return y; } // report y value double magval() const { return mag; } // report magnitude double angval() const { return ang; } // report angle void polar_mode() { mode = RECT; }; // set mode to POL void rect_mode() { mode = POL; }; // set mode to RECT VECTOR1 operator+(const VECTOR1& b) const; VECTOR1 operator-(const VECTOR1& b) const; VECTOR1 operator-() const; VECTOR1 operator*(double n) const; friend VECTOR1 operator*(double n, const VECTOR1& a); friend ostream& operator<<(ostream& os, const VECTOR1& v); }; }; #endif ,
VECTOR.cpp
#include "VECTOR.h" #include <cmath> namespace Vector { //double num = 180.0 / 3.14159265358979323846; const double num = 45.0 / atan(1.0); void VECTOR1::set_mag() { mag = sqrt(x * x + y * y); } void VECTOR1::set_ang() { if (x == 0.0 && y == 0.0) { ang = 0.0; } else { ang = atan2(y, x); } } void VECTOR1::set_x() { x = mag * cos(ang); } void VECTOR1::set_y() { y = mag * sin(ang); } VECTOR1::VECTOR1() { x = y = mag = ang = 0.0; mode = RECT; } VECTOR1::VECTOR1(double n1, double n2, Mode form) { mode = form; if (form == RECT) { x = n1; y = n2; set_mag(); set_ang(); } else if (form == POL) { mag = n1; ang = n2 / num; set_x(); set_y(); cout << "ang=" << ang << "mag=" << mag << endl; } else { cout << "Incorrect 3rd argument to VECTOR() -- "; cout << "vector set to 0\n"; x = y = mag = ang = 0.0; mode = RECT; } } void VECTOR1::reset(double n1, double n2, Mode form) { mode = form; if (form == RECT) { x = n1; y = n2; set_mag(); set_ang(); } else if (form == POL) { mag = n1; ang = n2 / num; set_x(); set_y(); } else { cout << "Incorrect 3rd argument to VECTOR() -- "; cout << "vector set to 0\n"; x = y = mag = ang = 0.0; mode = RECT; } } VECTOR1 VECTOR1::operator+(const VECTOR1& b) const { VECTOR1 temp; temp.x = x + b.x; temp.y = y + b.y; temp.set_mag();//类适合在一个对象中表示实体的不同方面(直角坐标和极坐标) temp.set_ang(); return temp; }//按照这种重载方式，不仅要更新直角坐标，还要更新极坐标， //按照下面用构造函数的方式就方便的多 VECTOR1 VECTOR1::operator-(const VECTOR1& b) const { return VECTOR1(x - b.x, y - b.y); } VECTOR1 VECTOR1::operator-() const { return VECTOR1(-x, -y); } VECTOR1 VECTOR1::operator*(double n) const { return VECTOR1(n * x, n * y); } VECTOR1 operator*(double n, const VECTOR1& a) { return a * n; } ostream& operator<<(ostream& os, const VECTOR1& v) { if (v.mode == VECTOR1::RECT) { os << "(x,y) = (" << v.x << "," << v.y << ")"; } else if (v.mode == VECTOR1::POL) { os << "(m,a) = (" << v.mag << "," << v.ang<< ")"; //cout << "d" << v.mag << v.ang * num; } else { os << "Vector object mode is invalid"; } return os; } }main.cpp
// VECTOR.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。 // #include <iostream> #include "VECTOR.h" using namespace Vector; int main() { std::cout << "Hello World!\n"; VECTOR1 a = VECTOR1(3.0, 4.0, VECTOR1::POL); VECTOR1 B = VECTOR1(6.0, 4.0, VECTOR1::RECT); VECTOR1 d = VECTOR1(8.0, 6.0, VECTOR1::POL); /*VECTOR1 a = VECTOR1(3.0, 4.0, RECT);*/ cout << "a: " << a << endl; cout << "B: " << B << endl; VECTOR1 c; c = a + B; cout << "c=a+B: " << c << endl; c = a - B; cout << "c=a-B: " << c << endl; c = -d; cout << "c=-d: " << c << endl; return 0; } // 运行程序: Ctrl + F5 或调试 >“开始执行(不调试)”菜单 // 调试程序: F5 或调试 >“开始调试”菜单 // 入门使用技巧: // 1. 使用解决方案资源管理器窗口添加/管理文件 // 2. 使用团队资源管理器窗口连接到源代码管理 // 3. 使用输出窗口查看生成输出和其他消息 // 4. 使用错误列表窗口查看错误 // 5. 转到“项目”>“添加新项”以创建新的代码文件，或转到“项目”>“添加现有项”以将现有代码文件添加到项目 // 6. 将来，若要再次打开此项目，请转到“文件”>“打开”>“项目”并选择 .sln 文件
类适合在一个对象中表示实体的不同方面
