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support bazel complie this project and format code.

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zhangxing
2023-03-30 00:15:11 +08:00
committed by light-city
parent 1f86192576
commit 7529ae3a55
636 changed files with 10025 additions and 9387 deletions
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25
practical_exercises/10_day_practice/day7/()运算符/重载()的时钟.cpp
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#include <iostream>
using namespace std;
class Time{
private:
int hh,mm,ss;
public:
Time(int h=0,int m=0,int s=0):hh(h),mm(m),ss(s){}
void operator()(int h,int m,int s) {
hh=h;
mm=m;
ss=s;
}
void ShowTime(){
cout<<hh<<":"<<mm<<":"<<ss<<endl;
}
};
int main(){
Time t1(12,10,11);
t1.ShowTime();
t1.operator()(23,20,34);
t1.ShowTime();
t1(10,10,10);
t1.ShowTime();
system("pause");
}

16
practical_exercises/10_day_practice/day7/=号运算符/=例题.cpp
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//例题ch.cppi
#include <iostream>
using namespace std;
class X{
public:
X &operator = (const X & x)
{cout << "a:"; return *this;};
};
int main ()
{
X obj1, obj2, obj3;
obj1 = obj2; //调用重载“=”
obj1.operator= (obj2); //调用重载“=”
obj1 = obj2 = obj3; //调用重载“=”
system("pause");
}

21
practical_exercises/10_day_practice/day7/[]与()例题/example1.cpp
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#include<iostream>
using namespace std;
class X
{public:
int operator() (int i=0)
{ cout << "X::operator(" << i << ")" << endl; return i; };
int operator() (int i, int j)
{ cout << "X::operator(" << i << "," << j << ")" << endl;
return i; };
int operator[] (int i)
{ cout << "X::operator[" << i << "]" << endl; return i; };
int operator[] (char * cp)
{ cout << "X::operator[" << cp << "]" << endl; return 0; };
};
int main (void)
{ X obj; int i = obj (obj (1), 2);
int a = obj[i]; int b = obj["abcd"];
cout<<"a="<<a<<endl;
cout<<"b="<<b<<endl;
system("pause");
}

50
practical_exercises/10_day_practice/day7/[]运算符/[]例题(重点).cpp
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//Eg8-9.cpp
#include <iostream>
#include <cstring>
using namespace std;
struct Person{ //职工基本信息的结构
double salary;
char *name;
};
class SalaryManaege{
Person *employ; //存放职工信息的数组
int max; //数组下标上界
int n; //数组中的实际职工人数
public:
SalaryManaege(int Max=0){
max=Max;
n=0;
employ=new Person[max];
}
double &operator[](char *Name) { //重载[]，返回引用
Person *p;
for(p=employ;p<employ+n;p++)
//如果存在处理
if(strcmp(p->name,Name)==0)
return p->salary;
//不存在情况处理
p=employ + n++;
p->name=new char[strlen(Name)+1];
strcpy(p->name,Name);
p->salary=0;
return p->salary;
}
void display(){
for(int i=0;i<n;i++)
cout<<employ[i].name<<" "<<employ[i].salary<<endl;
}
};
int main(){
SalaryManaege s(3);
s["张三"]=2188.88;
s["里斯"]=1230.07;
s["王无"]=3200.97;
cout<<"张三\t"<<s["张三"]<<endl; cout<<"里斯\t"<<s["里斯"]<<endl;
cout<<"王无\t"<<s["王无"]<<endl;
cout<<"-------下为display的输出--------\n\n";
s.display();
system("pause");
}

13
practical_exercises/10_day_practice/day7/binary_operator/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/binary_operator:operator`
# please run `bazel run //practical_exercises/10_day_practice/day7/binary_operator:friend_operator`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "operator",
srcs = ["operator.cpp"],
)
cc_binary(
name = "friend_operator",
srcs = ["friend_operator.cpp"],
)

85
practical_exercises/10_day_practice/day7/binary_operator/friend_operator.cpp Normal file
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/* 2.友元运算符实现.cpp */
/*
在C++的标准命名空间std中预定义了复数类Complex，
并且通过友元重载了Complex的各种运算，包括本程序中重载的+、-、*、/。
若使用using namespace std将std名字空间引入本程序，
则本程序中的Complex将与std名字空间中的Complex类的运算符重载函数产生冲突，引起编译错误。
*/
/*
对于不要求左值且可以交换参数次序的运算符（如+、-、*、/ 等运算符），
最好用非成员形式（包括友元和普通函数）的重载运算符函数实现。
*/
//解决前面的2+b问题。
#include <iostream>
class Complex {
private:
double r, i;
public:
Complex(double R = 0, double I = 0) : r(R), i(I){};
friend Complex operator+(Complex a, Complex b);
friend Complex operator-(Complex a, Complex b);
friend Complex operator*(Complex a, Complex b);
friend Complex operator/(Complex a, Complex b);
friend Complex operator+(Complex a, double b) {
return Complex(a.r + b, a.i);
}
friend Complex operator+(double a, Complex b) {
return Complex(a + b.r, b.i);
}
void display();
};
Complex operator+(Complex a, Complex b) {
return Complex(a.r + b.r, a.i + b.i);
}
Complex operator-(Complex a, Complex b) {
return Complex(a.r - b.r, a.i - b.i);
}
Complex operator*(Complex a, Complex b) {
Complex t;
t.r = a.r * b.r - a.i * b.i;
t.i = a.r * b.i + a.i * b.r;
return t;
}
Complex operator/(Complex a, Complex b) {
Complex t;
double x;
x = 1 / (b.r * b.r + b.i * b.i);
t.r = x * (a.r * b.r + a.i * b.i);
t.i = x * (a.i * b.r - a.r * b.i);
return t;
}
void Complex::display() {
std::cout << r;
if (i > 0)
std::cout << "+";
if (i != 0)
std::cout << i << "i" << std::endl;
}
int main(void) {
Complex c1(1, 2), c2(3, 4), c3, c4, c5, c6;
Complex a, b(2, 3);
Complex a1 = b + 2;
Complex a2 = 2 + b;
a1.display();
a2.display();
c3 = c1 + c2;
c4 = c1 - c2;
c5 = c1 * c2;
c6 = c1 / c2;
c1.display();
c2.display();
c3.display();
c4.display();
c5.display();
c6.display();
return 0;
}

63
practical_exercises/10_day_practice/day7/binary_operator/operator.cpp Normal file
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/* 1.类运算符重载.cpp */
//有复数类Complex，利用运算符重载实现复数的加、减、乘、除等复数运算。
#include <iostream>
using namespace std;
class Complex {
private:
double r, i;
public:
Complex(double R = 0, double I = 0) : r(R), i(I){};
Complex operator+(Complex b);
Complex operator-(Complex b);
Complex operator*(Complex b);
Complex operator/(Complex b);
void display();
};
Complex Complex::operator+(Complex b) { return Complex(r + b.r, i + b.i); }
Complex Complex::operator-(Complex b) { return Complex(r - b.r, i - b.i); }
//求复数相乘的算法
Complex Complex::operator*(Complex b) {
Complex t;
t.r = r * b.r - i * b.i;
t.i = r * b.i + i * b.r;
return t;
}
//求复数相除的算法
Complex Complex::operator/(Complex b) {
Complex t;
double x;
x = 1 / (b.r * b.r + b.i * b.i);
t.r = x * (r * b.r + i * b.i);
t.i = x * (i * b.r - r * b.i);
return t;
}
void Complex::display() {
cout << r;
if (i > 0)
cout << "+";
if (i != 0)
cout << i << "i" << endl;
//}display();
};
int main(void) {
Complex c1(1, 2), c2(3, 4), c3, c4, c5, c6;
Complex a, b(2, 3);
a = b + 2; //正确
// a=2+b; //错误
a.display();
c3 = c1 + c2;
c4 = c1 - c2;
c5 = c1 * c2;
c6 = c1 / c2;
c1.display();
c2.display();
c3.display();
c4.display();
c5.display();
c6.display();
return 0;
}

8
practical_exercises/10_day_practice/day7/brackets/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/brackets:brac`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "brac",
srcs = ["brac.cpp"],
)

25
practical_exercises/10_day_practice/day7/brackets/brac.cpp Normal file
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/* 重载()的时钟.cpp */
#include <iostream>
using namespace std;
class Time {
private:
int hh, mm, ss;
public:
Time(int h = 0, int m = 0, int s = 0) : hh(h), mm(m), ss(s) {}
void operator()(int h, int m, int s) {
hh = h;
mm = m;
ss = s;
}
void ShowTime() { cout << hh << ":" << mm << ":" << ss << endl; }
};
int main() {
Time t1(12, 10, 11);
t1.ShowTime();
t1.operator()(23, 20, 34);
t1.ShowTime();
t1(10, 10, 10);
t1.ShowTime();
}

8
practical_exercises/10_day_practice/day7/equal_operator/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/equal_operator:equal_operator`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "equal_operator",
srcs = ["equal_operator.cpp"],
)

18
practical_exercises/10_day_practice/day7/equal_operator/equal_operator.cpp Normal file
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/* =运算符重载.cpp */
//例题ch.cppi
#include <iostream>
using namespace std;
class X {
public:
X &operator=(const X &x) {
cout << "a:";
return *this;
};
};
int main() {
X obj1, obj2, obj3;
obj1 = obj2; //调用重载“=”
obj1.operator=(obj2); //调用重载“=”
obj1 = obj2 = obj3; //调用重载“=”
}

8
practical_exercises/10_day_practice/day7/example/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/example:example`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "example",
srcs = ["example.cpp"],
)

86
practical_exercises/10_day_practice/day7/example/example.cpp Normal file
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//设计一个字符串类String，通过运算符重载实现字符串的输入、输出以及+=、==、!=、<、>、>=、[
//]等运算。
#include <cstring>
#include <iostream>
using namespace std;
class String {
private:
int length; //字符串长度
char *sPtr; //存放字符串的指针
void setString(const char *s2);
friend ostream &operator<<(ostream &os, const String &s) {
return os << s.sPtr;
};
friend istream &operator>>(istream &is, String &s) {
return is >> s.sPtr;
}; //重载输入运算符
public:
String(const char * = "");
const String &operator=(const String &R) {
length = R.length;
strcpy(sPtr, R.sPtr);
return *this;
}; //重载赋值运算符 =
const String &operator+=(const String &R); //字符串的连接 +=
bool operator==(const String &R); //字符串的相等比较 ==
bool operator!=(const String &R); //字符串的不等比较 !=
bool operator!(); //判定字符串是否为空
bool operator<(const String &R) const; //字符串的小于比较 <
bool operator>(const String &R); //字符串的大于比较 >
bool operator>=(const String &R); //字符串的大于等于比较
char &operator[](int); //字符串的下标运算
~String(){};
};
const String &String::operator+=(const String &R) {
char *temp = sPtr;
length += R.length;
sPtr = new char[length + 1];
strcpy(sPtr, temp);
strcat(sPtr, R.sPtr);
delete[] temp;
return *this;
}
String::String(const char *str) {
sPtr = new char[strlen(str) + 1];
strcpy(sPtr, str);
length = strlen(str);
};
bool String::operator==(const String &R) { return strcmp(sPtr, R.sPtr) == 0; }
bool String::operator!=(const String &R) { return !(*this == R); }
bool String::operator!() { return length == 0; }
bool String::operator<(const String &R) const {
return strcmp(sPtr, R.sPtr) < 0;
}
bool String::operator>(const String &R) { return R < *this; }
bool String::operator>=(const String &R) { return !(*this < R); }
char &String::operator[](int subscript) { return sPtr[subscript]; }
int main() {
String s1("happy"), s2("new year"), s3;
cout << "s1 is " << s1 << "\ns2 is " << s2 << "\ns3 is " << s3
<< "\n比较s2和s1:"
<< "\ns2 ==s1结果是 " << (s2 == s1 ? "true" : "false")
<< "\ns2 != s1结果是 " << (s2 != s1 ? "true" : "false")
<< "\ns2 > s1结果是 " << (s2 > s1 ? "true" : "false")
<< "\ns2 < s1结果是 " << (s2 < s1 ? "true" : "false")
<< "\ns2 >= s1结果是 " << (s2 >= s1 ? "true" : "false");
cout << "\n\n测试s3是否为空: ";
if (!s3) {
cout << "s3是空串" << endl; // L3
cout << "把s1赋给s3的结果是：";
s3 = s1;
cout << "s3=" << s3 << "\n"; // L5
}
cout << "s1 += s2 的结果是：s1="; // L6
s1 += s2;
cout << s1; // L7
cout << "\ns1 += to you 的结果是："; // L8
s1 += " to you";
cout << "s1 = " << s1 << endl; // L9
s1[0] = 'H';
s1[6] = 'N';
s1[10] = 'Y';
cout << "s1 = " << s1 << "\n"; // L10
return 0;
}

8
practical_exercises/10_day_practice/day7/index_parentheses/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/subscript_operator:example`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "exexampleample1",
srcs = ["example.cpp"],
)

31
practical_exercises/10_day_practice/day7/index_parentheses/example.cpp Normal file
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/* []与() 运算符重载 */
#include <iostream>
using namespace std;
class X {
public:
int operator()(int i = 0) {
cout << "X::operator(" << i << ")" << endl;
return i;
};
int operator()(int i, int j) {
cout << "X::operator(" << i << "," << j << ")" << endl;
return i;
};
int operator[](int i) {
cout << "X::operator[" << i << "]" << endl;
return i;
};
int operator[](char *cp) {
cout << "X::operator[" << cp << "]" << endl;
return 0;
};
};
int main(void) {
X obj;
int i = obj(obj(1), 2);
int a = obj[i];
int b = obj["abcd"];
cout << "a=" << a << endl;
cout << "b=" << b << endl;
}

116
practical_exercises/10_day_practice/day7/readme.md
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@@ -1,15 +1,15 @@
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>C++<2B><>һ<EFBFBD><D2BB>ǿ<EFBFBD><C7BF><EFBFBD><EFBFBD><EFBFBD>ܡ<EFBFBD>ͨ<EFBFBD><CDA8><EFBFBD><EFBFBD><EFBFBD>أ<EFBFBD><D8A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>չC++<2B><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĺ<EFBFBD><C4B9>ܣ<EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD><EFBFBD><EFBFBD>ܹ<EFBFBD><DCB9><EFBFBD><EFBFBD><EFBFBD><EFBFBD>û<EFBFBD><C3BB>Զ<EFBFBD><D4B6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͣ<EFBFBD><CDA3><EFBFBD><EFBFBD>ӳ<EFBFBD><D3B3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֱ<EFBFBD><D6B1><EFBFBD>ԺͿɶ<CDBF><C9B6>ԡ<EFBFBD>
运算符重载是C++的一项强大功能。通过重载，可以扩展C++运算符的功能，使它们能够操作用户自定义的数据类型，增加程序代码的直观性和可读性。
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>Ա<EFBFBD><D4B1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>, <20><>Ԫ<EFBFBD><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һԪ<D2BB><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>, <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>++<2B><>--<2D><>[]<5D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>, thisָ<73><D6B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ؼ<EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><<<EFBFBD><EFBFBD>>><3E><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
本章主要介绍 类成员运算符重载与友元运算符重载, 二元运算符与一元运算符重载, 运算符++、--、[]、（）重载, this指针与运算符重载及 流运算符<<和>>的重载
һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ض<EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
一、重载二元运算符
1<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
1、二元运算符的调用形式与解析
aa@bb <EFBFBD>ɽ<EFBFBD><EFBFBD>ͳ<EFBFBD> aa.operator@(bb)
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͳ<EFBFBD> operator@(aa,bb)
aa@bb 可解释成 aa.operator@(bb)
或解释成 operator@(aa,bb)
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߶<EFBFBD><EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD>,<2C>Ͱ<EFBFBD><CDB0><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ؽ<EFBFBD><D8BD><EFBFBD>
如果两者都有定义,就按照重载解析
```c++
class X{
@@ -20,126 +20,126 @@ public:
void operator+(X,X);
void operator+(X,double);
```
2<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ
2、类运算符重载形式
<EFBFBD><EFBFBD>1<EFBFBD><EFBFBD><EFBFBD>Ǿ<EFBFBD>̬<EFBFBD><EFBFBD>Ա<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
（1）非静态成员运算符重载
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ա<EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD>ص<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ʲ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>1<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>thisָ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD>ݵġ<EFBFBD>
以类成员形式重载的运算符参数比实际参数少一个，第1个参数是以this指针隐式传递的。
```c++
class Complex{
double real,image;
public:
Complex operator+(Complex b){<EFBFBD><EFBFBD><EFBFBD><EFBFBD>}
Complex operator+(Complex b){……}
......
};
```
<EFBFBD><EFBFBD>2<EFBFBD><EFBFBD> <20><>Ԫ<EFBFBD><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
（2） 友元运算符重载
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD>أ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD>IJ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD>IJ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>磬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Complex<EFBFBD><EFBFBD><EFBFBD>ļӷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD>£<EFBFBD>
如果将运算符函数作为类的友元重载，它需要的参数个数就与运算符实际需要的参数个数相同。比如，若用友元函数重载Complex类的加法运算符，则形式如下：
```c++
class Complex{
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
friend Complex operator+(Complex a,Complex b); //<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
……
friend Complex operator+(Complex a,Complex b); //声明
//......
};
Complex operator+(Complex a,Complex b){<EFBFBD><EFBFBD><EFBFBD><EFBFBD>} //<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
Complex operator+(Complex a,Complex b){……} //定义
```
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
二、重载一元运算符
1<EFBFBD><EFBFBD>һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
1、一元运算符
һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֻ<EFBFBD><EFBFBD>Ҫһ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȡ<EFBFBD><EFBFBD>ַ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>&<26><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>?<3F><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӣ<EFBFBD>++<2B><><EFBFBD>ȡ<EFBFBD>
一元运算符只需要一个运算参数，如取地址运算符（&）、负数（?）、自增加（++）等。
2<EFBFBD><EFBFBD>һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽΪ<EFBFBD><EFBFBD>
2、一元运算符常见调用形式为：
@a <EFBFBD><EFBFBD> a@ //<EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ
@a 或 a@ //隐式调用形式
a.operator@() // <EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>@
a.operator@() // 显式调用一元运算符@
<EFBFBD><EFBFBD><EFBFBD>е<EFBFBD>@<40><><EFBFBD><EFBFBD>һԪ<D2BB><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>a<EFBFBD><61><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
其中的@代表一元运算符，a代表操作数。
@a<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǰ׺һԪ<EFBFBD><EFBFBD><EFBFBD>㣬<EFBFBD>硰++a<><61><EFBFBD><EFBFBD>
@a代表前缀一元运算，如“++a”；
a@<EFBFBD><EFBFBD>ʾ<EFBFBD><EFBFBD>׺<EFBFBD><EFBFBD><EFBFBD>㣬<EFBFBD>硰a++<2B><><EFBFBD><EFBFBD>
a@表示后缀运算，如“a++”。
3<EFBFBD><EFBFBD>@a<><61><EFBFBD><EFBFBD>C++<2B><><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ֮һ
3、@a将被C++解释为下面的形式之一
a.operator@()
operator@(a)
4.һԪ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ա<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD>£<EFBFBD>
4.一元运算符作为类成员函数重载时不需要参数，其形式如下：
```c++
class X{
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
T operator@(){<EFBFBD><EFBFBD><EFBFBD><EFBFBD>};
……
T operator@(){……};
}
```
T<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>@<40>ķ<EFBFBD><C4B7><EFBFBD><EFBFBD><EFBFBD><EFBFBD>͡<EFBFBD><CDA1><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD>Ͽ<EFBFBD><CFBF><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD><EFBFBD>Ա<EFBFBD><D4B1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ص<EFBFBD>һԪ<D2BB><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD>û<EFBFBD>в<EFBFBD><D0B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
T是运算符@的返回类型。从形式上看，作为类成员函数重载的一元运算符没有参数，但实际上它包含了一个隐含参数
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ö<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>thisָ<EFBFBD>롣
即调用对象的this指针。
5.ǰ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>(<28><>)<29><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>(<28><>)
5.前自增(减)与后自增(减)
C++<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ؼ<EFBFBD><EFBFBD><EFBFBD>int <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ַ<EFBFBD>ʽ
C++编译器可以通过在运算符函数参数表中是否插入关键字int 来区分这两种方式
```c++
//ǰ׺
//前缀
operator -- ();
operator -- (X & x);
//<EFBFBD><EFBFBD>׺
//后缀
operator -- (int);
operator -- (X & x, int);
```
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ظ<EFBFBD>ֵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>=
三、重载赋值运算符=
1<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>=<3D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
1、赋值运算符“=”的重载特殊性
<EFBFBD><EFBFBD>ֵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ô<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
赋值运算进行时将调用此运算符
ֻ<EFBFBD><EFBFBD><EFBFBD>ó<EFBFBD>Ա<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
只能用成员函数重载
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD>û<EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Զ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ɣ<EFBFBD><EFBFBD>ð汾<EFBFBD><EFBFBD><EFBFBD><EFBFBD>bit-by-bit<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
如果需要而没有定义时，编译器自动生成，该版本进行bit-by-bit拷贝
<EFBFBD>ġ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ظ<EFBFBD>ֵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>[]
四、重载赋值运算符[]
1<EFBFBD><EFBFBD>[ ]<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD>£<EFBFBD>
1、[ ]是一个二元运算符，其重载形式如下：
```c++
class X{
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
……
X& operator[](int n);
};
```
2<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>[]<5D><>Ҫע<D2AA><D7A2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
- []<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>1<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>thisָ<EFBFBD>봫<EFBFBD>ݵģ<EFBFBD><EFBFBD><EFBFBD>2<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>±<EFBFBD>
- <EFBFBD><EFBFBD><EFBFBD><EFBFBD>[]<5D>ȿ<EFBFBD><C8BF>Գ<EFBFBD><D4B3><EFBFBD><EFBFBD>ڸ<EFBFBD>ֵ<EFBFBD><D6B5><EFBFBD><EFBFBD>=<3D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ߣ<EFBFBD>Ҳ<EFBFBD><D2B2><EFBFBD>Գ<EFBFBD><D4B3><EFBFBD><EFBFBD>ڸ<EFBFBD>ֵ<EFBFBD><D6B5><EFBFBD><EFBFBD>=<3D><><EFBFBD><EFBFBD><EFBFBD>ұߣ<D2B1><DFA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>[]ʱ<><CAB1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>á<EFBFBD>
- **[]ֻ<EFBFBD>ܱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD>ķǾ<EFBFBD>̬<EFBFBD><EFBFBD>Ա<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**<2A><>
2、重载[]需要注意的问题
- []是一个二元运算符，其第1个参数是通过对象的this指针传递的，第2个参数代表数组的下标
- 由于[]既可以出现在赋值符“=”的左边，也可以出现在赋值符“=”的右边，所以重载运算符[]时常返回引用。
- **[]只能被重载为类的非静态成员函数，不能被重载为友元和普通函数**。
<EFBFBD>塢<EFBFBD><EFBFBD><EFBFBD><EFBFBD>( )
五、重载( )
1<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>( )<29>Ǻ<EFBFBD><C7BA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҳ<EFBFBD>ܱ<EFBFBD><DCB1><EFBFBD><EFBFBD>ء<EFBFBD><D8A1><EFBFBD>ֻ<EFBFBD>ܱ<EFBFBD><DCB1><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD>ij<EFBFBD>Ա<EFBFBD><D4B1><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
1、运算符( )是函数调用运算符，也能被重载。且只能被重载为类的成员函数。
2<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>( )<29><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><CABD><EFBFBD>£<EFBFBD>
2、运算符( )的重载形式如下：
```c++
class X{
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
X& operator( )(<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>);
}<EFBFBD><EFBFBD>
……
X& operator( )(参数表);
}；
```
<EFBFBD><EFBFBD><EFBFBD>еIJ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>԰<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
其中的参数表可以包括任意多个参数。
3<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>( )<29>ĵ<EFBFBD><C4B5><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><CABD><EFBFBD>£<EFBFBD>
3、运算符( )的调用形式如下：
X Obj; //<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
X Obj; //对象定义
Obj()(<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>); //<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ1
Obj()(参数表); //调用形式1
Obj(<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>); //<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ2
Obj(参数表); //调用形式2

8
practical_exercises/10_day_practice/day7/subscript_operator/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/subscript_operator:subscript_operator`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "subscript_operator",
srcs = ["subscript_operator.cpp"],
)

51
practical_exercises/10_day_practice/day7/subscript_operator/subscript_operator.cpp Normal file
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/* 重载[]运算符 */
// Eg8-9.cpp
#include <cstring>
#include <iostream>
using namespace std;
struct Person { //职工基本信息的结构
double salary;
char *name;
};
class SalaryManaege {
Person *employ; //存放职工信息的数组
int max; //数组下标上界
int n; //数组中的实际职工人数
public:
SalaryManaege(int Max = 0) {
max = Max;
n = 0;
employ = new Person[max];
}
double &operator[](char *Name) { //重载[]，返回引用
Person *p;
for (p = employ; p < employ + n; p++)
//如果存在处理
if (strcmp(p->name, Name) == 0)
return p->salary;
//不存在情况处理
p = employ + n++;
p->name = new char[strlen(Name) + 1];
strcpy(p->name, Name);
p->salary = 0;
return p->salary;
}
void display() {
for (int i = 0; i < n; i++)
cout << employ[i].name << " " << employ[i].salary << endl;
}
};
int main() {
SalaryManaege s(3);
s["张三"] = 2188.88;
s["里斯"] = 1230.07;
s["王无"] = 3200.97;
cout << "张三\t" << s["张三"] << endl;
cout << "里斯\t" << s["里斯"] << endl;
cout << "王无\t" << s["王无"] << endl;
cout << "-------下为display的输出--------\n\n";
s.display();
}

13
practical_exercises/10_day_practice/day7/unary_operator/BUILD Normal file
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# please run `bazel run //practical_exercises/10_day_practice/day7/unary_operator:time_increase`
# please run `bazel run //practical_exercises/10_day_practice/day7/unary_operator:time_counter`
load("@rules_cc//cc:defs.bzl", "cc_binary")
cc_binary(
name = "time_increase",
srcs = ["time_increase.cpp"],
)
cc_binary(
name = "time_counter",
srcs = ["time_counter.cpp"],
)

48
practical_exercises/10_day_practice/day7/unary_operator/time_counter.cpp Normal file
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/* 计数器前后自增.cpp */
//设计一个计数器counter，用类成员重载自增运算符实现计数器的自增，用友元重载实现计数器的自减。
#include <iostream>
using namespace std;
class Counter {
private:
int n;
public:
Counter(int i = 0) : n(i){};
Counter operator++();
Counter operator++(int);
friend Counter operator--(Counter &c);
friend Counter operator--(Counter &c, int);
void display();
};
Counter Counter::operator++() {
++n;
return *this;
}
Counter Counter::operator++(int) {
Counter t = *this;
n++;
return t;
}
Counter operator--(Counter &c) {
--c.n;
return c;
}
Counter operator--(Counter& c, int) {
Counter t(c.n);
c.n--;
return t;
}
void Counter::display() { cout << "counter number=" << n << endl; }
int main(int argc, char const *argv[]) {
Counter a;
++a;
a.display();
a++;
a.display();
--a;
a.display();
a--;
a.display();
return 0;
}

75
practical_exercises/10_day_practice/day7/unary_operator/time_increase.cpp Normal file
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/* 秒钟自增运算.cpp */
//设计一个时间类Time，它能够完成秒钟的自增运算。
#include <iostream>
using namespace std;
class Time {
private:
int hour, minute, second;
public:
Time(int h, int m, int s);
Time operator++();
//友元重载需要参数
friend Time operator--(Time &t);
void display();
};
Time::Time(int h, int m, int s) {
hour = h;
minute = m;
second = s;
if (hour >= 24)
hour = 0;
if (minute >= 60)
minute = 0;
if (second >= 60)
second = 0;
}
Time Time::operator++() {
++second;
if (second >= 60) {
second = 0;
++minute;
if (minute >= 60) {
minute = 0;
++hour;
if (hour >= 24)
hour = 0;
}
}
return *this;
}
Time operator--(Time &t) {
--t.second;
if (t.second < 0) {
t.second = 59;
--t.minute;
if (t.minute < 0) {
t.minute = 59;
--t.hour;
if (t.hour < 0)
t.hour = 23;
}
}
return t;
}
void Time::display() { cout << hour << ":" << minute << ":" << second << endl; }
int main(int argc, char const *argv[]) {
Time t1(23, 59, 59);
t1.display();
++t1; //隐式调用
t1.display();
t1.operator++(); //显式调用
t1.display();
Time t2(24, 60, 60);
t2.display();
++t2;
t2.display();
--t2;
t2.display();
return 0;
}

76
practical_exercises/10_day_practice/day7/一元运算符/秒钟自增运算.cpp
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//设计一个时间类Time，它能够完成秒钟的自增运算。
#include<iostream>
using namespace std;
class Time{
private:
int hour,minute,second;
public:
Time(int h,int m, int s);
Time operator++();
//友元重载需要参数
friend Time operator--(Time &t);
void display();
};
Time::Time(int h, int m, int s){
hour=h;
minute=m;
second=s;
if (hour>=24)
hour=0;
if (minute>=60)
minute=0;
if (second>=60)
second=0;
}
Time Time::operator++(){
++second;
if (second>=60){
second=0;
++minute;
if(minute>=60){
minute=0;
++hour;
if(hour>=24)
hour=0;
}
}
return *this;
}
Time operator--(Time &t){
--t.second;
if (t.second<0){
t.second=59;
--t.minute;
if(t.minute<0){
t.minute=59;
--t.hour;
if(t.hour<0)
t.hour=23;
}
}
return t;
}
void Time::display(){
cout<<hour<<":"<<minute<<":"<<second<<endl;
}
int main(int argc, char const *argv[])
{
Time t1(23,59,59);
t1.display();
++t1; //隐式调用
t1.display();
t1.operator++(); //显式调用
t1.display();
Time t2(24,60,60);
t2.display();
++t2;
t2.display();
--t2;
t2.display();
system("pause");
return 0;
}

49
practical_exercises/10_day_practice/day7/一元运算符/计数器前后自增.cpp
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//设计一个计数器counter，用类成员重载自增运算符实现计数器的自增，用友元重载实现计数器的自减。
#include<iostream>
using namespace std;
class Counter{
private:
int n;
public:
Counter(int i=0):n(i){};
Counter operator++();
Counter operator++(int);
friend Counter operator--(Counter &c);
friend Counter operator--(Counter &c,int);
void display();
};
Counter Counter::operator++(){
++n;
return *this;
}
Counter Counter::operator++(int){
Counter t=*this;
n++;
return t;
}
Counter operator--(Counter &c){
--c.n;
return c;
}
Counter operator--(Counter &c,int){
Counter t=*this;
c.n--;
return t;
}
void Counter::display(){
cout<<"counter number="<<n<<endl;
}
int main(int argc, char const *argv[])
{
Counter a;
++a;
a.display();
a++;
a.display();
--a;
a.display();
a--;
a.display();
system("pause");
return 0;
}

67
practical_exercises/10_day_practice/day7/二元运算符/1.类运算符重载.cpp
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//有复数类Complex，利用运算符重载实现复数的加、减、乘、除等复数运算。
#include<iostream>
using namespace std;
class Complex {
private:
double r,i;
public:
Complex(double R=0,double I=0):r(R),i(I){};
Complex operator+(Complex b);
Complex operator-(Complex b);
Complex operator*(Complex b);
Complex operator/(Complex b);
void display();
};
Complex Complex::operator +(Complex b)
{
return Complex(r+b.r,i+b.i);
}
Complex Complex::operator -(Complex b)
{
return Complex(r-b.r,i-b.i);
}
//求复数相乘的算法
Complex Complex::operator *(Complex b)
{
Complex t;
t.r=r*b.r-i*b.i;
t.i=r*b.i+i*b.r;
return t;
}
//求复数相除的算法
Complex Complex::operator /(Complex b) {
Complex t;
double x;
x=1/(b.r*b.r+b.i*b.i);
t.r=x*(r*b.r+i*b.i);
t.i=x*(i*b.r-r*b.i);
return t;
}
void Complex::display(){
cout<<r;
if (i>0) cout<<"+";
if (i!=0) cout<<i<<"i"<<endl;
//}display();
};
int main(void) {
Complex c1(1,2),c2(3,4),c3,c4,c5,c6;
Complex a,b(2,3);
a=b+2; //正确
// a=2+b; //错误
a.display();
c3=c1+c2;
c4=c1-c2;
c5=c1*c2;
c6=c1/c2;
c1.display();
c2.display();
c3.display();
c4.display();
c5.display();
c6.display();
system("pause");
return 0;
}

85
practical_exercises/10_day_practice/day7/二元运算符/2.友元运算符实现.cpp
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/*
在C++的标准命名空间std中预定义了复数类Complex，
并且通过友元重载了Complex的各种运算，包括本程序中重载的+、-、*、/。
若使用using namespace std将std名字空间引入本程序，
则本程序中的Complex将与std名字空间中的Complex类的运算符重载函数产生冲突，引起编译错误。
*/
/*
对于不要求左值且可以交换参数次序的运算符（如+、-、*、/ 等运算符），
最好用非成员形式（包括友元和普通函数）的重载运算符函数实现。
*/
//解决前面的2+b问题。
#include<iostream>
class Complex{
private:
double r,i;
public:
Complex(double R=0,double I=0):r(R),i(I){};
friend Complex operator+(Complex a, Complex b);
friend Complex operator-(Complex a, Complex b);
friend Complex operator*(Complex a, Complex b);
friend Complex operator/(Complex a, Complex b);
friend Complex operator+(Complex a,double b){
return Complex(a.r+b,a.i);
}
friend Complex operator+(double a,Complex b){
return Complex(a+b.r,b.i);
}
void display();
};
Complex operator+(Complex a, Complex b){
return Complex(a.r+b.r,a.i+b.i);
}
Complex operator-(Complex a, Complex b){
return Complex(a.r-b.r,a.i-b.i);
}
Complex operator*(Complex a, Complex b){
Complex t;
t.r = a.r*b.r-a.i*b.i;
t.i = a.r*b.i+a.i*b.r;
return t;
}
Complex operator/(Complex a, Complex b){
Complex t;
double x;
x = 1/(b.r*b.r+b.i*b.i);
t.r = x*(a.r*b.r+a.i*b.i);
t.i = x*(a.i*b.r-a.r*b.i);
return t;
}
void Complex::display(){
std::cout<<r;
if(i>0)
std::cout<<"+";
if(i!=0)
std::cout<<i<<"i"<<std::endl;
}
int main(void) {
Complex c1(1,2),c2(3,4),c3,c4,c5,c6;
Complex a,b(2,3);
Complex a1=b+2;
Complex a2=2+b;
a1.display();
a2.display();
c3=c1+c2;
c4=c1-c2;
c5=c1*c2;
c6=c1/c2;
c1.display();
c2.display();
c3.display();
c4.display();
c5.display();
c6.display();
system("pause");
return 0;
}

91
practical_exercises/10_day_practice/day7/综合例题/重要.cpp
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//设计一个字符串类String，通过运算符重载实现字符串的输入、输出以及+=、==、!=、<、>、>=、[ ]等运算。
#include <iostream>
#include <cstring>
using namespace std;
class String
{
private:
int length; //字符串长度
char *sPtr; //存放字符串的指针
void setString(const char *s2);
friend ostream &operator<<(ostream &os, const String &s)
{
return os << s.sPtr;
};
friend istream &operator>>(istream &is, String &s)
{
return is >> s.sPtr;
}; //重载输入运算符
public:
String(const char * = "");
const String &operator=(const String &R)
{
length = R.length;
strcpy(sPtr, R.sPtr);
return *this;
}; //重载赋值运算符 =
const String &operator+=(const String &R); //字符串的连接 +=
bool operator==(const String &R); //字符串的相等比较 ==
bool operator!=(const String &R); //字符串的不等比较 !=
bool operator!(); //判定字符串是否为空
bool operator<(const String &R) const; //字符串的小于比较 <
bool operator>(const String &R); //字符串的大于比较 >
bool operator>=(const String &R); //字符串的大于等于比较
char &operator[](int); //字符串的下标运算
~String(){};
};
const String &String::operator+=(const String &R)
{
char *temp = sPtr;
length += R.length;
sPtr = new char[length + 1];
strcpy(sPtr, temp);
strcat(sPtr, R.sPtr);
delete[] temp;
return *this;
}
String::String(const char *str)
{
sPtr = new char[strlen(str) + 1];
strcpy(sPtr, str);
length = strlen(str);
};
bool String::operator==(const String &R) { return strcmp(sPtr, R.sPtr) == 0; }
bool String::operator!=(const String &R) { return !(*this == R); }
bool String::operator!() { return length == 0; }
bool String::operator<(const String &R) const { return strcmp(sPtr, R.sPtr) < 0; }
bool String::operator>(const String &R) { return R < *this; }
bool String::operator>=(const String &R) { return !(*this < R); }
char &String::operator[](int subscript) { return sPtr[subscript]; }
int main()
{
String s1("happy"), s2("new year"), s3;
cout << "s1 is " << s1 << "\ns2 is " << s2 << "\ns3 is " << s3
<< "\n比较s2和s1:"
<< "\ns2 ==s1结果是 " << (s2 == s1 ? "true" : "false")
<< "\ns2 != s1结果是 " << (s2 != s1 ? "true" : "false")
<< "\ns2 > s1结果是 " << (s2 > s1 ? "true" : "false")
<< "\ns2 < s1结果是 " << (s2 < s1 ? "true" : "false")
<< "\ns2 >= s1结果是 " << (s2 >= s1 ? "true" : "false");
cout << "\n\n测试s3是否为空: ";
if (!s3)
{
cout << "s3是空串" << endl; //L3
cout << "把s1赋给s3的结果是：";
s3 = s1;
cout << "s3=" << s3 << "\n"; //L5
}
cout << "s1 += s2 的结果是：s1="; //L6
s1 += s2;
cout << s1; //L7
cout << "\ns1 += to you 的结果是："; //L8
s1 += " to you";
cout << "s1 = " << s1 << endl; //L9
s1[0] = 'H';
s1[6] = 'N';
s1[10] = 'Y';
cout << "s1 = " << s1 << "\n"; //L10
system("pause");
return 0;
}