/** @file list3201.cpp */
/** Listing 32-1. Mystery Program */
#include <iostream>
#include <ostream>
struct point
{
point()
: x_(0.0), y_(0.0)
{
std::cout << "default constructor\n";
}
point(double x, double y)
: x_(x), y_(y)
{
std::cout << "constructor(" << x << ", " << y << ")\n";
}
double x_;
double y_;
};
int main()
{
point pt();// 此处存在二义性，好像是定义了一函数，函数返回类型是point，所以如果是要定义一个point对象pt，pt后面不能加括号（）；
point pt; // 正确调用默认的构造函数
std::cout<<pt.x_<<std::endl; // 调用point()默认构造函数
}
/** @file list3203.cpp */
/** Listing 32-3. Problem with istream Iterators */
#include <algorithm>
#include <iostream>
#include <istream>
#include <iterator>
#include <ostream>
#include <vector>
int main()
{
using namespace std;
/// 如果是 vector<int> orig ( istream_iterator<int>(cin)), (istream_iterator<int>() );
/// 编译器会把 orig 当成是一个函数，有二义性，在编译时会处理成 vector<int> orig istream_iterator<int>(cin), istream_iterator<int>()
/// 为避免歧义，在参数外面加上 括号 ，如下
vector<int> orig( ( istream_iterator<int>(cin) ), ( istream_iterator<int>() ) );
vector<int>::iterator zero(find(orig.begin(), orig.end(), 0));
vector<int> from_zero(zero, orig.end());
copy(from_zero.begin(), from_zero.end(), ostream_iterator<int>(cout, "\n"));
}
/** @file list3206.cpp */
/** Listing 32-6. const Member Functions for Class point */
#include <cmath> // for sqrt and atan
#include <cmath>
#include <iostream>
#include <ostream>
struct point
{
/// Distance to the origin.
double distance()
const
{
std::cout<<"x="<<x<<std::endl;
return std::sqrt(x*x + y*y);
}
/// Angle relative to x-axis.
double angle()
const
{
return std::atan2(y, x);
}
/// Add an offset to x and y.
void offset(double off)
{
offset(off, off);
}
/// Add an offset to x and an offset to y
void offset(double xoff, double yoff)
{
x = x + xoff;
y = y + yoff;
}
/// Scale x and y.
void scale(double mult)
{
this->scale(mult, mult);
}
/// Scale x and y.
void scale(double xmult, double ymult)
{
this->x = this->x * xmult;
this->y = this->y * ymult;
}
double x;
double y;
};
// void print_polar(point pt) //此处既可以调用非const方法，也可以调用const方法
void print_polar(point const& pt)
{
// point 对象的const引用 pt 只可以调用 const 方法，
std::cout << "{ r=" << pt.distance() << ", angle=" << pt.angle() << " }\n";
}
void print_cartesian(point const& pt)
{
std::cout << "{ x=" << pt.x << ", y=" << pt.y << " }\n";
}
int main()
{
point p1, p2;
double const pi = 3.141592653589792;
p1.x = std::cos(pi / 3);
p1.y = std::sin(pi / 3);
print_polar(p1);
print_cartesian(p1);
p2 = p1;
p2.scale(4.0);
print_polar(p2);
print_cartesian(p2);
p2.offset(0.0, -2.0);
print_polar(p2);
print_cartesian(p2);
}
#include<iostream>
using namespace std;
class Counter
{
int value;
public:
Counter(int v = 0)
{
value = v;
}
Counter(Counter& c)
{
value = c.value;
cout << "拷贝构造函数被调用" << endl;
}
Counter& operator=(Counter& c) // 重载赋值运算符
{
value = c.value;
cout << "赋值运算符重载函数被调用" << endl;
return *this;
}
void display()
{
cout << value << endl;
}
};
void main()
{
Counter countOne(5);
countOne.display();
Counter countTwo = countOne; //创建新对象，拷贝构造函数被调用
countTwo.display();
countTwo = countOne; //对象已存在，赋值运算符重载函数被调用
countTwo.display();
}
#include<iostream>
using namespace std;
class Complex //复数类声明
{
public: //外部接口
Complex(double r = 0, double i = 0) //构造函数
{
real = r; imag = i;
}
void display() //输出复数
{
cout << real;
if (imag >= 0) cout << "+" << imag;
else cout << imag;
cout << "i" << endl;
}
Complex operator + (Complex &c2); //运算符+重载成员函数
Complex operator + (double r); //运算符+重载成员函数
private: //私有数据成员
double real; //复数实部
double imag; //复数虚部
};
Complex Complex::operator +(Complex &c2) //重载运算符+函数实现
{
cout << "address : " << &c2 << std::endl;
Complex temp;
temp.real = real + c2.real;
temp.imag = imag + c2.imag;
return temp;
}
Complex Complex::operator + (double r)
{
Complex temp;
temp.real = real + r;
temp.imag = imag;
return temp;
}
int main() //主函数
{
Complex c1(1, 2), c2(3, 4), c3, c4, c5; //定义复数类的对象
cout << "c1 address " << &c1 << std::endl;
cout << "c2 address " << &c2 << std::endl;
cout << "c3 address " << &c3 << std::endl;
cout << "c4 address " << &c4 << std::endl;
cout << "c5 address " << &c5 << std::endl;
cout << "c1 = "; c1.display();
cout << "c2 = "; c2.display();
c3 = c1 + c2; //使用重载运算符完成复数加法
cout << "c3 = c1+c2=";
c3.display();
c4 = c1 + c2 + c3; //使用重载运算符完成复数加法, 顺序相当于(c1 + c2)+ c3
cout << "c4 = c1 + c2 + c3= ";
c4.display();
c5 = c1 + 10;
cout << "c5 = c5 + 10 = ";
c5.display();
return 0;
}