一.输入输出
1 #include <iostream> 2 using namespace std; 3 4 class Complex 5 { 6 public: 7 Complex() 8 { 9 real = 0; 10 imag = 0; 11 } 12 13 Complex(double r) 14 { 15 real = r; 16 imag = 0; 17 } 18 19 Complex(double r, double i) 20 { 21 real = r; 22 imag = i; 23 } 24 25 Complex operator+(const Complex &c) const 26 { 27 Complex s; 28 s.real = real + c.real; 29 s.imag = imag + c.imag; 30 return s; 31 } 32 33 Complex operator-(const Complex &c) 34 { 35 Complex s; 36 s.real = real - c.real; 37 s.imag = imag - c.imag; 38 return s; 39 } 40 41 double real, imag; 42 }; 43 44 istream& operator>>(istream &in, Complex &c) 45 { 46 return in >> c.real >> c.imag; 47 } 48 ostream& operator<<(ostream& out, Complex &c); 49 int main() 50 { 51 Complex s; 52 cin >> s;//1 2 53 cout << s.real << " " << s.imag << endl;//1 2 54 return 0; 55 }
二.赋值
1 #include <iostream> 2 using namespace std; 3 4 class Point 5 { 6 public: 7 8 Point() 9 { 10 x = 0; 11 y = 0; 12 } 13 14 Point(int a, int b) 15 { 16 x = a; 17 y = b; 18 } 19 20 Point& operator=(const Point& p) 21 { 22 x = p.x; 23 y = p.y; 24 return *this; 25 } 26 int x, y; 27 }; 28 29 ostream& operator<<(ostream &out, Point p) 30 { 31 return out << p.x << " " << p.y << endl; 32 } 33 34 35 36 int main() 37 { 38 Point p1, p2, p3(3, 4); 39 p1 = p2 = p3; 40 cout << p1 << p2; 41 /* 42 3 4 43 3 4 44 */ 45 return 0; 46 }
1 #include <iostream> 2 using namespace std; 3 4 class String 5 { 6 public: 7 String(const char *s) 8 { 9 length = strlen(s); 10 p = new char[length + 1]; 11 strcpy(p, s); 12 } 13 14 private: 15 int length; 16 char *p; 17 }; 18 19 void fun(String &aa) 20 { 21 String c("789"); 22 c = aa; 23 } 24 25 26 int main() 27 { 28 String a("1"), b("x"); 29 b = a;//内存泄漏，b.p没有释放 30 fun(a);//a.p将指向一个未定义区域，指针悬浮 31 a = a;//检测两边是否相等 32 return 0; 33 }
1 const String& String::operator=(const String &right) 2 { 3 if (this != &right)//防止自我赋值 4 { 5 delete[] p;//防止内存泄漏 6 length = right.length;//取新字符串长度 7 p = new char[length + 1];//分配内存 8 for (int i = 0; i < length; i++) 9 { 10 p[i] = right.p[i];//复制 11 } 12 } 13 return *this; 14 }
1 Complex& operator=(string str) 2 { 3 char *p = new char[str.length + 1]; 4 strcpy(p, str.c_str()); 5 r = atof(strtok(p, "+")); 6 i = atof(strtok(NULL, "i")); 7 return *this; 8 }
三.下标操作符
1 #include <iostream> 2 using namespace std; 3 4 class CharArray 5 { 6 public: 7 CharArray(int len) 8 { 9 length = len; 10 p = new char[length]; 11 } 12 13 char& operator[](int i) 14 { 15 static char ch = 0; 16 if (i >= 0 && i < length) 17 { 18 return p[i]; 19 } 20 else 21 { 22 cout << " out" << endl; 23 return ch; 24 } 25 } 26 27 private: 28 int length; 29 char *p; 30 }; 31 32 int main() 33 { 34 CharArray str1(6); 35 char *str2 = "abcdefg"; 36 for (int i = 0; i < 7; i++) 37 { 38 str1[i] = str2[i];//str2[6]保存在ch里 39 } 40 for (int i = 0; i < 7; i++) 41 { 42 cout << str1[i]; 43 } 44 cout << endl; 45 /* 46 out 47 abcdef 48 out 49 g 50 */ 51 return 0; 52 }
四.函数调用操作符
1 #include <iostream> 2 using namespace std; 3 4 class F 5 { 6 public: 7 double operator()(double x, double y) const 8 { 9 return 2 * x + y; 10 } 11 }; 12 13 int main() 14 { 15 F f; 16 cout << f(1.5, 3.2) << endl;//6.2 17 return 0; 18 }
1 #include <iostream> 2 using namespace std; 3 4 class Array 5 { 6 public: 7 Array() 8 { 9 num = new int[1]; 10 } 11 Array(int i, int j) 12 { 13 row = i; 14 col = j; 15 num = new int[row * col]; 16 } 17 int* operator[](int i) 18 { 19 return &num[i * col]; 20 } 21 int operator()(int i, int j) 22 { 23 return num[i * col + j]; 24 } 25 ~Array() 26 { 27 delete[] num; 28 } 29 30 private: 31 int *num, row, col; 32 }; 33 34 int main() 35 { 36 Array a(3, 4); 37 for (int i = 0; i < 3; i++) 38 { 39 for (int j = 0; j < 4; j++) 40 { 41 a[i][j] = 1; 42 } 43 } 44 cout << a(1, 1) << endl; // 1 45 return 0; 46 }
五.自增/自减
#include <iostream> using namespace std; class A { public: A() { value = 0; } A(int t) { value = t; } A operator++() { value++; return *this; } A operator++(int) { A t; t.value = value++; return t; /* A a = *this; ++(*this); return a; */ } int value; }; ostream& operator<<(ostream &out, A a) { return out << a.value << endl; } int main() { A a(10); cout << a++; // 10 cout << ++a; // 12 return 0; }
五.转型操作符
声明中不能包含形参和返回类型，但函数体中必须包含return语句，用来返回转型结果。
1 #include <iostream> 2 using namespace std; 3 4 class A 5 { 6 public: 7 A(float num) 8 { 9 value = num; 10 } 11 operator int() 12 { 13 return static_cast<int>(value) + 10; 14 } 15 16 float value; 17 }; 18 19 int main() 20 { 21 A a(8.0); 22 int i = a; 23 cout << i << endl;//18 24 return 0; 25 }
六.内存管理
new, new[], delete, delete[]
void *类::operator new(size_t size);第一个参数必须是size_t，数值等于将被创建的对象大小
void 类::operator delete(void *p);第一个参数必须是void *