support bazel complie this project and format code.

2023-03-30 00:15:11 +08:00
parent 1f86192576
commit 7529ae3a55
636 changed files with 10025 additions and 9387 deletions
--- a/practical_exercises/key_exercises/BUILD
+++ b/practical_exercises/key_exercises/BUILD
@@ -0,0 +1,78 @@
+# please run `bazel run //practical_exercises/key_exercises:output`
+# please run `bazel run //practical_exercises/key_exercises:clock`
+# please run `bazel run //practical_exercises/key_exercises:read_file`
+# please run `bazel run //practical_exercises/key_exercises:operator_circle`
+# please run `bazel run //practical_exercises/key_exercises:io_operator`
+# please run `bazel run //practical_exercises/key_exercises:stack`
+# please run `bazel run //practical_exercises/key_exercises:try`
+# please run `bazel run //practical_exercises/key_exercises:override`
+# please run `bazel run //practical_exercises/key_exercises:io_operator_overload`
+# please run `bazel run //practical_exercises/key_exercises:array_template`
+# please run `bazel run //practical_exercises/key_exercises:array`
+# please run `bazel run //practical_exercises/key_exercises:map_insert_look`
+# please run `bazel run //practical_exercises/key_exercises:func_temp`
+# please run `bazel run //practical_exercises/key_exercises:bracket_overloading`
+# please run `bazel run //practical_exercises/key_exercises:operator_cast`
+
+load("@rules_cc//cc:defs.bzl", "cc_binary")
+
+cc_binary(
+    name = "output",
+    srcs = ["output.cpp"],
+)
+cc_binary(
+    name = "clock",
+    srcs = ["clock.cpp"],
+)
+cc_binary(
+    name = "read_file",
+    srcs = ["read_file.cpp"],
+)
+cc_binary(
+    name = "operator_circle",
+    srcs = ["operator_circle.cpp"],
+)
+cc_binary(
+    name = "io_operator",
+    srcs = ["io_operator.cpp"],
+)
+cc_binary(
+    name = "stack",
+    srcs = ["stack.cpp"],
+)
+cc_binary(
+    name = "try",
+    srcs = ["try.cpp"],
+)
+cc_binary(
+    name = "override",
+    srcs = ["override.cpp"],
+)
+cc_binary(
+    name = "io_operator_overload",
+    srcs = ["io_operator_overload.cpp"],
+)
+cc_binary(
+    name = "array_template",
+    srcs = ["array_template.cpp"],
+)
+cc_binary(
+    name = "array",
+    srcs = ["array.cpp"],
+)
+cc_binary(
+    name = "map_insert_look",
+    srcs = ["map_insert_look.cpp"],
+)
+cc_binary(
+    name = "func_temp",
+    srcs = ["func_temp.cpp"],
+)
+cc_binary(
+    name = "bracket_overloading",
+    srcs = ["bracket_overloading.cpp"],
+)
+cc_binary(
+    name = "operator_cast",
+    srcs = ["operator_cast.cpp"],
+)
--- a/practical_exercises/key_exercises/README.md
+++ b/practical_exercises/key_exercises/README.md
@@ -1,26 +1,26 @@
 ## 重点实战练习

-├── [中括号重载.cpp](中括号重载.cpp)
-├── [时钟++运算符重载.cpp](时钟++运算符重载.cpp)
-├── [运算符重载之强制转换.cpp](运算符重载之强制转换.cpp)
-└── [重载圆括号的时钟.cpp](重载圆括号的时钟.cpp)
+├── [中括号重载.cpp](bracket_overloading.cpp)
+├── [时钟++运算符重载.cpp](clock.cpp)
+├── [运算符重载之强制转换.cpp](operator_cast.cpp)
+└── [重载圆括号的时钟.cpp](operator_circle.cpp)

-├── [函数模板.cpp](函数模板.cpp)
+├── [函数模板.cpp](func_temp.cpp)

-├── [动态数组.cpp](动态数组.cpp)
+├── [动态数组.cpp](array.cpp)

-├── [字典插入与查找.cpp](字典插入与查找.cpp)
+├── [字典插入与查找.cpp](map_insert_look.cpp)

-├── [异常捕获.cpp](异常捕获.cpp)
+├── [异常捕获.cpp](try.cpp)

-├── [类模板之栈.cpp](类模板之栈.cpp)
+├── [类模板之栈.cpp](stack.cpp)

-├── [类模板特化之数组.cpp](类模板特化之数组.cpp)
+├── [类模板特化之数组.cpp](array_template.cpp)

-├── [继承与封装.cpp](继承与封装.cpp)
+├── [继承与封装.cpp](override.cpp)

-├── [读写文件综合题.cpp](读写文件综合题.cpp)
-├── [输入输出运算符重载.cpp](输入输出运算符重载.cpp)
-├── [输入输出重载.cpp](输入输出重载.cpp)
-├── [输出格式.cpp](输出格式.cpp)
+├── [读写文件综合题.cpp](read_file.cpp)
+├── [输入输出运算符重载.cpp](io_operator_overload.cpp)
+├── [输入输出重载.cpp](io_operator.cpp)
+├── [输出格式.cpp](output.cpp)

--- a/practical_exercises/key_exercises/array.cpp
+++ b/practical_exercises/key_exercises/array.cpp
@@ -0,0 +1,14 @@
+/* 数组.cpp */
+#include <cstring>
+#include <iostream>
+
+int main() {
+
+  char *sPtr;
+  const char *s = "hello";
+  sPtr = new char[strlen(s) + 1];
+  strncpy(sPtr, s, strlen(s));
+  std::cout << sPtr << std::endl;
+  delete sPtr;
+  return 0;
+}
--- a/practical_exercises/key_exercises/array_template.cpp
+++ b/practical_exercises/key_exercises/array_template.cpp
@@ -0,0 +1,80 @@
+/* 类模板特化之数组.cpp */
+#include <cstring>
+#include <iostream>
+using namespace std;
+#define MAXSIZE 5
+template <class T> class Array {
+public:
+  Array() {
+    for (int i = 0; i < MAXSIZE; i++) {
+      array[i] = 0;
+    }
+  }
+
+  T &operator[](int i);
+  void Sort();
+
+private:
+  T array[MAXSIZE];
+};
+
+template <class T> T &Array<T>::operator[](int i) {
+  if (i < 0 || i > MAXSIZE - 1) {
+    cout << "数组下标越界！" << endl;
+    exit(0);
+  }
+  return array[i];
+}
+
+template <class T> void Array<T>::Sort() {
+  int p, j;
+  for (int i = 0; i < MAXSIZE - 1; i++) {
+    p = i;
+    for (j = i + 1; j < MAXSIZE; j++) {
+      if (array[p] < array[j])
+        p = j;
+    }
+    T t;
+    t = array[i];
+    array[i] = array[p];
+    array[p] = t;
+  }
+}
+template <> void Array<char *>::Sort() {
+  int p, j;
+  for (int i = 0; i < MAXSIZE - 1; i++) {
+    p = i;
+    for (j = i + 1; j < MAXSIZE; j++) {
+      if (strcmp(array[p], array[j]) < 0)
+        p = j;
+    }
+    char *t = array[i];
+    array[i] = array[p];
+    array[p] = t;
+  }
+}
+
+int main(int argc, char const *argv[]) {
+  Array<int> a1;
+  Array<char *> b1;
+  a1[0] = 1;
+  a1[1] = 23;
+  a1[2] = 6;
+  a1[3] = 3;
+  a1[4] = 9;
+  a1.Sort();
+  for (int i = 0; i < 5; i++)
+    cout << a1[i] << "\t";
+  cout << endl;
+  b1[0] = "x1";
+  b1[1] = "ya";
+  b1[2] = "ad";
+  b1[3] = "be";
+  b1[4] = "bc";
+  b1.Sort();
+  for (int i = 0; i < 5; i++)
+    cout << b1[i] << "\t";
+  cout << endl;
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/bracket_overloading.cpp
+++ b/practical_exercises/key_exercises/bracket_overloading.cpp
@@ -0,0 +1,51 @@
+/* 中括号重载.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];
+  }
+  //返回引用特性是可以直接在放在左值，直接使用
+  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;
+  }
+  ~SalaryManaege() { delete[] employ; }
+};
+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();
+}
--- a/practical_exercises/key_exercises/clock.cpp
+++ b/practical_exercises/key_exercises/clock.cpp
@@ -0,0 +1,85 @@
+/* 时钟++运算符重载.cpp */
+#include <cmath>
+#include <iostream>
+using namespace std;
+
+/*
+ *  时钟类
+ */
+class Clock {
+private:
+  int Hour, Minute, Second;
+
+public:
+  Clock(int h = 0, int m = 0, int s = 0);
+  void ShowTime();
+  Clock &operator++();
+  Clock operator++(int);
+};
+
+/*
+ *  时钟类构造函数
+ */
+Clock::Clock(int h, int m, int s) {
+  if (h >= 0 && h < 24 && m >= 0 && m < 60 && s >= 0 && s < 60) {
+    Hour = h;
+    Minute = m;
+    Second = s;
+  } else
+    cout << "输入的时间格式错误!" << endl;
+}
+
+/*
+ *  显示时间
+ */
+void Clock::ShowTime() {
+  cout << Hour << ":" << Minute << ":" << Second << endl;
+}
+
+/*
+ *  时间递增一秒（重载前缀++运算符）
+ */
+Clock &Clock::operator++() {
+  Second++;
+  if (Second >= 60) {
+    Second = Second - 60;
+    Minute++;
+    if (Minute >= 60) {
+      Minute = Minute - 60;
+      Hour++;
+      Hour = Hour % 24;
+    }
+  }
+  return *this;
+}
+
+/*
+ *  时间递增一秒（重载后缀++运算符）
+ */
+Clock Clock::operator++(int) {
+  Clock old = *this;
+  ++(*this);
+  return old;
+}
+
+/*
+ *  主函数
+ */
+int main() {
+  Clock myClock(23, 59, 59);
+  cout << "初始化显示时间为:\t\t";
+  myClock.ShowTime();
+
+  cout << "执行myClock++后的时间为:\t";
+
+  //先执行ShowTime()，输出myClock=23:59:59，
+  //再执行myClock++，此时myClock=00:00:00
+  (myClock++).ShowTime();
+
+  cout << "执行++myClock后的时间为:\t";
+
+  //先执行++myClock，此时myClock=00:00:01
+  //再执行ShowTime()，输出myClock=00:00:01
+  (++myClock).ShowTime();
+  
+}
--- a/practical_exercises/key_exercises/函数模板.cpp
+++ b/practical_exercises/key_exercises/函数模板.cpp
@@ -1,20 +1,19 @@
+/* 函数模板.cpp */
 #include <cstring>
 #include <iostream>
 using namespace std;

-template <class T>
-T compareMax(T t1, T t2) {
-  return t1 > t2 ? t1 : t2;
-}
+template <class T> T compareMax(T t1, T t2) { return t1 > t2 ? t1 : t2; }

 template <>
 const char *compareMax<const char *>(const char *s1, const char *s2) {
-  cout << "[for debug]" << " call compareMax template" << endl;
+  cout << "[for debug]"
+       << " call compareMax template" << endl;
  return strcmp(s1, s2) >= 0 ? s1 : s2;
 }
 int main(int argc, char const *argv[]) {
  cout << compareMax(1, 2) << endl;
  cout << compareMax("asda", "qweq") << endl;
-  system("pause");
+  
  return 0;
 }
--- a/practical_exercises/key_exercises/io_operator.cpp
+++ b/practical_exercises/key_exercises/io_operator.cpp
@@ -0,0 +1,40 @@
+/* 输入输出重载.cpp */
+#include <iostream>
+using namespace std;
+#include <cstring>
+class Sales {
+private:
+  char name[10];
+  char id[18];
+  int age;
+
+public:
+  Sales(char *Name, char *ID, int Age);
+  friend Sales &operator<<(ostream &os, Sales &s);
+  friend Sales &operator>>(istream &is, Sales &s);
+};
+
+Sales::Sales(char *Name, char *ID, int Age) {
+  strcpy(name, Name);
+  strcpy(id, ID);
+  age = Age;
+}
+
+Sales &operator<<(ostream &os, Sales &s) {
+  os << s.name << "\t" << s.id << "\t" << s.age << endl;
+  return s;
+}
+
+Sales &operator>>(istream &is, Sales &s) {
+  cout << "输入雇员的姓名，身份证，年龄：\n";
+  is >> s.name >> s.id >> s.age;
+}
+
+int main(int argc, char const *argv[]) {
+  Sales s("张三", "15611", 26);
+  cout << s;
+  cin >> s;
+  cout << s;
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/io_operator_overload.cpp
+++ b/practical_exercises/key_exercises/io_operator_overload.cpp
@@ -0,0 +1,43 @@
+/* 输入输出运算符重载.cpp */
+/*
+   有一销售人员类Sales，其数据成员有姓名name，身份证号id，年龄age。
+   重载输入/输出运算符实现对Sales类数据成员的输入和输出。
+ */
+#include <cstring>
+#include <iostream>
+using namespace std;
+class Sales {
+private:
+  char name[10];
+  char id[18];
+  int age;
+
+public:
+  Sales(char *Name, char *ID, int Age);
+
+  friend Sales &operator<<(ostream &os, Sales &s); //重载输出运算符
+  friend Sales &operator>>(istream &is, Sales &s); //重载输入运算符
+};
+Sales::Sales(char *Name, char *ID, int Age) {
+  strcpy(name, Name);
+  strcpy(id, ID);
+  age = Age;
+}
+Sales &operator<<(ostream &os, Sales &s) {
+  os << s.name << "\t"; //输出姓名
+  os << s.id << "\t";   //输出身份证号
+  os << s.age << endl;  //输出年龄
+  return s;
+}
+Sales &operator>>(istream &is, Sales &s) {
+  cout << "输入雇员的姓名，身份证号，年龄" << endl;
+  is >> s.name >> s.id >> s.age;
+  return s;
+}
+int main() {
+  Sales s1("杜康", "214198012111711", 40); // L1
+  cout << s1;                              // L2
+  cout << endl;                            // L3
+  cin >> s1;                               // L4
+  cout << s1;                              // L5
+}
--- a/practical_exercises/key_exercises/map_insert_look.cpp
+++ b/practical_exercises/key_exercises/map_insert_look.cpp
@@ -0,0 +1,80 @@
+/* 字典插入与查找.cpp */
+#include <cstring>
+#include <iostream>
+#include <map>
+using namespace std;
+
+int main(int argc, char const *argv[]) {
+  map<const char *, const char *> mp;
+  map<const char *, const char *>::iterator iter;
+  const char key[3][20] = {"img", "system", "ip"};
+  const char value[3][20] = {"d:/a.img", "win7", "193.68.6.3"};
+
+  // make_pair插入
+  for (int i = 0; i < 2; i++) {
+    mp.insert(make_pair(key[i], value[i]));
+  }
+  // pair<const char*,const char*>插入
+  mp.insert(pair<const char *, const char *>(key[2], value[2]));
+
+  //数组插入方式
+  mp["addr"] = "中国";
+  //迭代器取出元素
+  //循环取出元素
+  for (iter = mp.begin(); iter != mp.end(); iter++) {
+    cout << iter->first << "\t" << iter->second << endl;
+  }
+  char key1[20];
+  cout << "请输入按key查找：";
+  cin.getline(key1, 20);
+  //查找元素
+  for (iter = mp.begin(); iter != mp.end(); iter++) {
+    if (strcmp(iter->first, key1) == 0) {
+      cout << iter->first << "查找出来了！"
+           << "对应的值为：" << iter->second << endl;
+    }
+  }
+
+  //第一种删除方式
+  // find只能用于查找数组建立的形式！并且不支持输入用cin等
+  iter = mp.find("addr");
+  if (iter != mp.end()) {
+    cout << iter->first << "按照key查找出来了！"
+         << "对应的value为：" << iter->second << endl;
+    cout << "开始删除元素！" << endl;
+    mp.erase(iter);
+    // break;
+  }
+  //第二种方式删除
+  //按照key删除元素
+  char drop_key[20];
+  //按照value删除元素
+  char drop_value[20];
+  cout << "请输入按key删除：";
+  cin.getline(drop_key, 20);
+  cout << "请输入按value删除：";
+  cin.getline(drop_value, 20);
+  for (iter = mp.begin(); iter != mp.end(); iter++) {
+    if (strcmp(iter->first, drop_key) == 0) {
+      cout << iter->first << "按照key查找出来了！"
+           << "对应的value为：" << iter->second << endl;
+      cout << "开始删除元素！" << endl;
+      mp.erase(iter);
+      break;
+    }
+    if (strcmp(iter->second, drop_value) == 0) {
+      cout << iter->second << "value查找出来了！"
+           << "对应的key为：" << iter->first << endl;
+      cout << "开始删除元素！" << endl;
+      mp.erase(iter);
+      break;
+    }
+  }
+  cout << "------删除元素以后--------\n";
+  //循环取出元素
+  for (iter = mp.begin(); iter != mp.end(); iter++) {
+    cout << iter->first << "\t" << iter->second << endl;
+  }
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/operator_cast.cpp
+++ b/practical_exercises/key_exercises/operator_cast.cpp
@@ -0,0 +1,41 @@
+/* 运算符重载之强制转换.cpp */
+/*
+有一个类Circle，设计该类的类型转换函数，当将Circle对象转换成int型时，返回圆的半径；当将它转换成double型时，就返回圆的周长；当将它转换成float型时，就返回圆的面积。
+*/
+
+/*
+
+类型转换函数没有参数。
+类型转换函数没有返回类型。
+类型转换函数必须返回将要转换成的type类型数据。
+
+*/
+
+#include <iostream>
+using namespace std;
+class Circle {
+private:
+  double x, y, r;
+
+public:
+  Circle(double x1, double y1, double r1) {
+    x = x1;
+    y = y1;
+    r = r1;
+  }
+  operator int() { return int(r); }
+  operator double() { return 2 * 3.14 * r; }
+  operator float() { return (float)3.14 * r * r; }
+};
+int main() {
+  Circle c(2.3, 3.4, 2.5);
+  int r = c;         //调用operator int()，将Circle类型转换成int
+  double length = c; //调用operator double()，转换成double
+  float area = c;    //调用operator float()，将Circle类型转换成float
+  double len = (double)c; //将Cirlce类型对象强制转换成double
+  cout << r << endl;
+  cout << length << endl;
+  cout << len << endl;
+  cout << area << endl;
+  
+}
--- a/practical_exercises/key_exercises/operator_circle.cpp
+++ b/practical_exercises/key_exercises/operator_circle.cpp
@@ -0,0 +1,25 @@
+/* 重载圆括号的时钟.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();
+  
+}
--- a/practical_exercises/key_exercises/output.cpp
+++ b/practical_exercises/key_exercises/output.cpp
@@ -0,0 +1,19 @@
+/* 输出格式.cpp */
+#include <iomanip>
+#include <iostream>
+using namespace std;
+
+int main(int argc, char const *argv[]) {
+  char s[20] = "this is a string";
+  double digit = -36.96656;
+  cout << setw(30) << left << setfill('*') << s << endl;
+  cout << dec << setprecision(4) << digit << endl;
+  cout << dec << 15 << endl;
+  // setbase(int x)设置进制后，后面所有操作都是按照这个进制来计算！
+  cout << setbase(10) << 15 << endl;
+  //四舍五入,并保留2位有效数组
+  float x = 6.6937;
+  cout << float(int(x * 1000 + 0.5) / 1000.0) << endl;
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/override.cpp
+++ b/practical_exercises/key_exercises/override.cpp
@@ -0,0 +1,87 @@
+/* 继承与封装.cpp */
+#include <cstring>
+#include <iostream>
+
+using namespace std;
+class Employee {
+public:
+  Employee(const char *name, const char *id) {
+    strcpy(Name, name);
+    strcpy(Id, id);
+  }
+  char *getName() { return Name; }
+  char *getId() { return Id; }
+  void display() { cout << Name << "\t" << Id << endl; }
+
+private:
+  char Name[20];
+  char Id[20];
+};
+
+class Manager : public Employee {
+public:
+  //直接调用构造方法传递，基类构造方法有参数，派生类必须通过构造方法，在初始化列表中传递参数
+  Manager(const char *name, const char *id, int week) : Employee(name, id) {
+    WeeklySalary = week * 1000;
+  }
+  void display() {
+    cout << "经理：" << getName() << "\t" << getId() << "\t" << WeeklySalary
+         << endl;
+  }
+
+private:
+  int WeeklySalary;
+};
+
+class SaleWorker : public Employee {
+public:
+  SaleWorker(const char *name, const char *id, int profit, int x)
+      : Employee(name, id) {
+    workerMoney = baseMoney + x * 0.05 * profit;
+  }
+  void display() {
+    cout << "销售员：" << getName() << "\t" << getId() << "\t" << workerMoney
+         << endl;
+  }
+
+private:
+  float baseMoney = 800.0;
+  float workerMoney;
+};
+class HourWorker : public Employee {
+public:
+  HourWorker(const char *name, const char *id, int h) : Employee(name, id) {
+    TotalMoney = h * hourMoney;
+  }
+  void display() {
+    cout << "小时工：" << getName() << "\t" << getId() << "\t" << TotalMoney
+         << endl;
+  }
+
+private:
+  float hourMoney = 100.0;
+  float TotalMoney;
+};
+
+int main(int argc, char const *argv[]) {
+  cout << "请输入工作周：";
+  int week;
+  cin >> week;
+  Manager m("小王", "11111111", week);
+  m.display();
+  cout << "请输入销售利润：";
+  int profit;
+  cin >> profit;
+  cout << "请输入销售件数：";
+  int x;
+  cin >> x;
+  SaleWorker s("小李", "222222", profit, x);
+  s.display();
+  cout << "请输入工作小时：";
+  int hour;
+  cin >> hour;
+  HourWorker h("小何", "333333", hour);
+  h.display();
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/read_file.cpp
+++ b/practical_exercises/key_exercises/read_file.cpp
@@ -0,0 +1,74 @@
+/* 读写文件综合题.cpp */
+#include <cstring>
+#include <fstream>
+#include <iostream>
+#include <vector>
+using namespace std;
+
+class Person {
+public:
+  Person() {}
+  Person(char *name, char *id, int math, int chinese, int english) {
+    strcpy(Name, name);
+    strcpy(Id, id);
+    Math = math;
+    Chinese = chinese;
+    English = english;
+    Sum = Math + Chinese + English;
+  }
+
+  void display() {
+    cout << Name << "\t" << Id << "\t" << Math << "\t" << Chinese << "\t"
+         << English << "\t" << Sum << endl;
+  }
+
+private:
+  char Name[20];
+  char Id[20];
+  int Math;
+  int Chinese;
+  int English;
+  int Sum;
+};
+
+int main(int argc, char const *argv[]) {
+  char ch;
+  char Name[20], Id[20];
+  int Math, Chinese, English;
+  fstream ioFile;
+  ioFile.open("d:/per.dat", ios::out | ios::app);
+  cout << "---------建立学生档案信息----------\n";
+  do {
+    cout << "请输入姓名：";
+    cin >> Name;
+    cout << "请输入身份证号：";
+    cin >> Id;
+    cout << "请输入数学成绩：";
+    cin >> Math;
+    cout << "请输入汉语成绩：";
+    cin >> Chinese;
+    cout << "请输入英语成绩：";
+    cin >> English;
+    Person per(Name, Id, Math, Chinese, English);
+    ioFile.write((char *)&per, sizeof(per));
+    cout << "您是否继续建档？(Y/y)  ";
+    cin >> ch;
+  } while (ch == 'y' || ch == 'Y');
+  ioFile.close();
+  ioFile.open("d://per.dat", ios::in);
+  Person p;
+  ioFile.read((char *)&p, sizeof(p));
+  vector<Person> v;
+  vector<Person>::iterator vt;
+  while (!ioFile.eof()) {
+    v.push_back(p);
+    ioFile.read((char *)&p, sizeof(p));
+  }
+  ioFile.close();
+  cout << "---------输出档案信息-----------" << endl;
+  for (vt = v.begin(); vt != v.end(); vt++) {
+    (*vt).display();
+  }
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/stack.cpp
+++ b/practical_exercises/key_exercises/stack.cpp
@@ -0,0 +1,60 @@
+/* 类模板之栈.cpp */
+#include <iostream>
+
+using namespace std;
+
+template <typename T, int MAXSIZE>
+
+class Stack {
+public:
+  Stack() {}
+  void init() { top = -1; }
+  bool isFull() {
+    if (top >= MAXSIZE - 1)
+      return true;
+    else
+      return false;
+  }
+  bool isEmpty() {
+    if (top == -1)
+      return true;
+    else
+      return false;
+  }
+  void push(T e);
+  T pop();
+
+private:
+  T elems[MAXSIZE];
+  int top;
+};
+
+template <typename T, int MAXSIZE> void Stack<T, MAXSIZE>::push(T e) {
+  if (!isFull()) {
+    elems[++top] = e;
+  } else {
+    cout << "栈已满，请不要再加入元素！";
+    return;
+  }
+}
+template <typename T, int MAXSIZE> T Stack<T, MAXSIZE>::pop() {
+  if (!isEmpty()) {
+    return elems[top--];
+  } else {
+    cout << "栈已空，请不要再弹出元素！";
+    return 0;
+  }
+}
+
+int main(int argc, char const *argv[]) {
+  Stack<int, 10> s1;
+  s1.init();
+  int i;
+  for (i = 1; i < 11; i++)
+    s1.push(i);
+  for (i = 1; i < 11; i++)
+    cout << s1.pop() << "\t";
+  cout << endl;
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/try.cpp
+++ b/practical_exercises/key_exercises/try.cpp
@@ -0,0 +1,25 @@
+/* 异常捕获.cpp */
+#include <iostream>
+using namespace std;
+//函数异常可以抛出去由主函数来处理
+void fun(int x) {
+  try {
+    if (x == 0)
+      throw "异常";
+  } catch (...) {
+    cout << "in fun" << endl;
+    throw 1;
+  }
+}
+
+int main(int argc, char const *argv[]) {
+
+  try {
+    fun(0);
+  } catch (int n) {
+    cout << "in main" << endl;
+  }
+
+  
+  return 0;
+}
--- a/practical_exercises/key_exercises/中括号重载.cpp
+++ b/practical_exercises/key_exercises/中括号重载.cpp
@@ -1,58 +0,0 @@
-#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];
-    }
-    //返回引用特性是可以直接在放在左值，直接使用
-    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;
-    }
-    ~SalaryManaege() {
-        delete[] employ;
-    }
-};
-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();
-}
--- a/practical_exercises/key_exercises/动态数组.cpp
+++ b/practical_exercises/key_exercises/动态数组.cpp
@@ -1,14 +0,0 @@
-#include<iostream>
-#include<cstring>
-
-
-int main() {
-  
-  char *sPtr;        	 
-  const char* s="hello";
-  sPtr = new char[strlen(s)+1];
-  strncpy(sPtr,s,strlen(s)); 
-  std::cout << sPtr << std::endl;
-  delete sPtr;
-  return  0;
-}
--- a/practical_exercises/key_exercises/字典插入与查找.cpp
+++ b/practical_exercises/key_exercises/字典插入与查找.cpp
@@ -1,78 +0,0 @@
-#include<iostream>
-#include<map>
-#include<cstring>
-using namespace std;
-
-
-
-int main(int argc, char const *argv[])
-{
-    map<const char*,const char*> mp;
-    map<const char*,const char*>::iterator iter;
-    const char key[3][20]={"img","system","ip"};
-    const char value[3][20]={"d:/a.img","win7","193.68.6.3"};
-    
-    //make_pair插入
-    for(int i=0;i<2;i++){
-        mp.insert(make_pair(key[i],value[i]));
-    }
-    //pair<const char*,const char*>插入
-    mp.insert(pair<const char*,const char*>(key[2],value[2]));
-
-    //数组插入方式
-    mp["addr"]="中国";
-    //迭代器取出元素
-    //循环取出元素
-    for(iter=mp.begin();iter!=mp.end();iter++){
-        cout<<iter->first<<"\t"<<iter->second<<endl;
-    }
-    char key1[20];
-    cout<<"请输入按key查找：";
-    cin.getline(key1,20);
-    //查找元素
-    for(iter=mp.begin();iter!=mp.end();iter++){
-        if(strcmp(iter->first,key1)==0){
-            cout<<iter->first<<"查找出来了！"<<"对应的值为："<<iter->second<<endl;
-        }
-    }
-   
-    //第一种删除方式
-    //find只能用于查找数组建立的形式！并且不支持输入用cin等
-    iter=mp.find("addr");
-    if(iter!=mp.end()){
-        cout<<iter->first<<"按照key查找出来了！"<<"对应的value为："<<iter->second<<endl;
-        cout<<"开始删除元素！"<<endl;
-        mp.erase(iter);
-        // break;
-    }
-    //第二种方式删除
-     //按照key删除元素
-    char drop_key[20];
-    //按照value删除元素
-    char drop_value[20];
-    cout<<"请输入按key删除：";
-    cin.getline(drop_key,20);
-    cout<<"请输入按value删除：";
-    cin.getline(drop_value,20);
-    for(iter=mp.begin();iter!=mp.end();iter++){
-        if(strcmp(iter->first,drop_key)==0){
-            cout<<iter->first<<"按照key查找出来了！"<<"对应的value为："<<iter->second<<endl;
-            cout<<"开始删除元素！"<<endl;
-            mp.erase(iter);
-            break;
-        }
-        if(strcmp(iter->second,drop_value)==0){
-            cout<<iter->second<<"value查找出来了！"<<"对应的key为："<<iter->first<<endl;
-            cout<<"开始删除元素！"<<endl;
-            mp.erase(iter);
-            break;
-        }
-    }
-    cout<<"------删除元素以后--------\n";
-    //循环取出元素
-    for(iter=mp.begin();iter!=mp.end();iter++){
-        cout<<iter->first<<"\t"<<iter->second<<endl;
-    }
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/异常捕获.cpp
+++ b/practical_exercises/key_exercises/异常捕获.cpp
@@ -1,25 +0,0 @@
-#include<iostream>
-using namespace std;
-//函数异常可以抛出去由主函数来处理
-void fun(int x){
-    try{
-        if (x==0)
-            throw "异常";
-    }catch(...){
-        cout<<"in fun"<<endl;
-        throw 1;
-    }
-}
-
-int main(int argc, char const *argv[])
-{
-
-    try{
-        fun(0);
-    }catch(int n){
-        cout<<"in main"<<endl;
-    }
-
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/时钟++运算符重载.cpp
+++ b/practical_exercises/key_exercises/时钟++运算符重载.cpp
@@ -1,93 +0,0 @@
-#include<iostream>   
-#include<cmath>   
-using namespace std;   
-  
-/*  
- *  时钟类  
- */  
-class Clock    
-{   
-private:    
-    int Hour, Minute, Second;   
-public:    
-    Clock(int h=0, int m=0, int s=0);   
-    void ShowTime();   
-    Clock& operator ++();    
-    Clock operator ++(int);   
-};   
-  
-/*  
- *  时钟类构造函数  
- */  
-Clock::Clock(int h,int m, int s)   
-{   
-    if(h>=0 && h<24 && m>=0 && m<60 && s>=0 && s<60)   
-    {   
-        Hour = h;   
-        Minute =m;    
-        Second= s;   
-    }   
-    else  
-        cout<<"输入的时间格式错误!"<<endl;   
-}   
-  
-/*  
- *  显示时间  
- */  
-void Clock::ShowTime()   
-{   
-    cout<<Hour<<":"<<Minute<<":"<<Second<<endl;   
-}   
-  
-/*  
- *  时间递增一秒（重载前缀++运算符）  
- */  
-Clock& Clock::operator ++()    
-{    
-    Second++;   
-    if (Second >= 60)   
-    {   
-        Second = Second - 60;   
-        Minute++;   
-        if (Minute >= 60)   
-        {   
-            Minute = Minute - 60;   
-            Hour++;   
-            Hour = Hour % 24;   
-        }   
-    }   
-    return *this;   
-}   
-  
-/*  
- *  时间递增一秒（重载后缀++运算符）  
- */  
-Clock Clock::operator ++(int)   
-{   
-    Clock old = *this;   
-    ++(*this);   
-    return old;   
-}   
-  
-/*  
- *  主函数  
- */  
-int main()   
-{   
-    Clock myClock(23,59,59);   
-    cout<<"初始化显示时间为:\t\t";   
-    myClock.ShowTime();   
-  
-    cout<<"执行myClock++后的时间为:\t";   
-  
-    //先执行ShowTime()，输出myClock=23:59:59，   
-    //再执行myClock++，此时myClock=00:00:00   
-    (myClock++).ShowTime();   
-  
-    cout<<"执行++myClock后的时间为:\t";   
-  
-    //先执行++myClock，此时myClock=00:00:01   
-    //再执行ShowTime()，输出myClock=00:00:01   
-    (++myClock).ShowTime();   
-    system("pause");
-}  
--- a/practical_exercises/key_exercises/类模板之栈.cpp
+++ b/practical_exercises/key_exercises/类模板之栈.cpp
@@ -1,63 +0,0 @@
-#include<iostream>
-
-using namespace std;
-
-template<typename T,int MAXSIZE>
-
-class Stack{
-    public:
-        Stack(){}
-        void init(){
-            top=-1;
-        }
-        bool isFull(){
-            if(top>=MAXSIZE-1)
-                return true;
-            else
-                return false;
-        }
-        bool isEmpty(){
-            if(top==-1)
-                return true;
-            else
-                return false;
-        }
-        void push(T e);
-        T pop();
-
-    private:
-        T elems[MAXSIZE];
-        int top;
-};
-
-template<typename T,int MAXSIZE> void Stack<T,MAXSIZE>::push(T e){
-    if(!isFull()){
-        elems[++top]=e;
-    }
-    else{
-        cout<<"栈已满，请不要再加入元素！";
-        return;
-    }
-}
-template<typename T,int MAXSIZE> T Stack<T,MAXSIZE>::pop(){
-    if(!isEmpty()){
-        return elems[top--];
-    }
-    else{
-        cout<<"栈已空，请不要再弹出元素！";
-        return 0;
-    }
-}
-
-int main(int argc, char const *argv[])
-{
-    Stack<int,10> s1;
-    s1.init();
-    int i;
-    for(i=1;i<11;i++) 
-        s1.push(i);
-    for(i=1;i<11;i++) cout<<s1.pop()<<"\t";
-    cout<<endl;
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/类模板特化之数组.cpp
+++ b/practical_exercises/key_exercises/类模板特化之数组.cpp
@@ -1,76 +0,0 @@
-#include<iostream>
-#include<cstring>
-using namespace std;
-#define MAXSIZE 5
-template<class T>
-class Array{
-    public:
-        Array(){
-            for(int i=0;i<MAXSIZE;i++){
-                array[i]=0;
-            }
-        }
-
-        T &operator[](int i);
-        void Sort();
-
-
-    private:
-        T array[MAXSIZE];
-};
-
-template<class T> T& Array<T>::operator[](int i){
-    if(i<0||i>MAXSIZE-1){
-        cout<<"数组下标越界！"<<endl;
-        exit(0);
-    }
-    return array[i];
-}
-
-template<class T> void Array<T>::Sort(){
-    int p,j;
-    for(int i=0;i<MAXSIZE-1;i++){
-        p=i;
-        for(j=i+1;j<MAXSIZE;j++){
-            if(array[p]<array[j])
-                p=j;
-        }
-        T t;
-        t=array[i];
-        array[i]=array[p];
-        array[p]=t;
-    }   
-}
-template<> void Array<char *>::Sort(){
-    int p,j;
-    for(int i=0;i<MAXSIZE-1;i++){
-        p=i;
-        for(j=i+1;j<MAXSIZE;j++){
-            if(strcmp(array[p],array[j])<0)
-                p=j;
-        }
-        char* t=array[i];
-        array[i]=array[p];
-        array[p]=t;
-    }
-}
-
-int main(int argc, char const *argv[])
-{
-    Array<int> a1;
-    Array<char*>b1;
-    a1[0]=1;a1[1]=23;a1[2]=6;
-    a1[3]=3; a1[4]=9; 	
-    a1.Sort();
-    for(int i=0;i<5;i++) 
-    cout<<a1[i]<<"\t";
-    cout<<endl;	
-    b1[0]="x1";	b1[1]="ya";	b1[2]="ad";
-    b1[3]="be";	b1[4]="bc";	
-    b1.Sort();
-    for(int i=0;i<5;i++)
-    cout<<b1[i]<<"\t";
-    cout<<endl;	
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/继承与封装.cpp
+++ b/practical_exercises/key_exercises/继承与封装.cpp
@@ -1,90 +0,0 @@
-#include<iostream>
-#include<cstring>
-
-using namespace std;
-class Employee{
-    public:
-        Employee(const char *name,const char *id){
-            strcpy(Name,name);
-            strcpy(Id,id);
-        }
-        char* getName(){
-            return Name;
-        }
-        char* getId(){
-            return Id;
-        }
-        void display(){
-            cout<<Name<<"\t"<<Id<<endl;
-        }
-
-    private:
-        char Name[20];
-        char Id[20];
-};
-
-
-class Manager:public Employee{
-    public:
-        //直接调用构造方法传递，基类构造方法有参数，派生类必须通过构造方法，在初始化列表中传递参数
-        Manager(const char *name,const char *id,int week):Employee(name,id){
-            WeeklySalary=week*1000;
-        }
-        void display(){
-            cout<<"经理："<<getName()<<"\t"<<getId()<<"\t"<<WeeklySalary<<endl;
-        }
-    private:
-        int WeeklySalary;
-};
-
-class SaleWorker:public Employee{
-    public:
-        SaleWorker(const char*name,const char *id,int profit,int x):Employee(name,id){
-            workerMoney=baseMoney+x*0.05*profit;
-        }
-        void display(){
-            cout<<"销售员："<<getName()<<"\t"<<getId()<<"\t"<<workerMoney<<endl;
-        }
-
-    private:
-        float baseMoney=800.0;
-        float workerMoney;
-};
-class HourWorker:public Employee{
-    public:
-        HourWorker(const char*name,const char *id,int h):Employee(name,id){
-            TotalMoney=h*hourMoney;
-        }
-        void display(){
-            cout<<"小时工："<<getName()<<"\t"<<getId()<<"\t"<<TotalMoney<<endl;
-        }
-    private:
-        float hourMoney=100.0;
-        float TotalMoney;
-};
-
-
-
-int main(int argc, char const *argv[])
-{
-    cout<<"请输入工作周：";
-    int week;
-    cin>>week;
-    Manager m("小王","11111111",week);
-    m.display();
-    cout<<"请输入销售利润：";
-    int profit;
-    cin>>profit;
-    cout<<"请输入销售件数：";
-    int x;
-    cin>>x;
-    SaleWorker s("小李","222222",profit,x);
-    s.display();
-    cout<<"请输入工作小时：";
-    int hour;
-    cin>>hour;
-    HourWorker h("小何","333333",hour);
-    h.display();
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/读写文件综合题.cpp
+++ b/practical_exercises/key_exercises/读写文件综合题.cpp
@@ -1,73 +0,0 @@
-
-#include<iostream>
-#include<fstream>
-#include<cstring>
-#include<vector>
-using namespace std;
-
-class Person{
-    public:
-        Person(){}
-        Person(char *name,char *id,int math,int chinese,int english){
-            strcpy(Name,name);
-            strcpy(Id,id);
-            Math=math;
-            Chinese=chinese;
-            English=english;
-            Sum=Math+Chinese+English;
-        }
-
-        void display(){
-            cout<<Name<<"\t"<<Id<<"\t"<<Math<<"\t"<<Chinese<<"\t"<<English<<"\t"<<Sum<<endl;
-        }
-    private:
-        char Name[20];
-        char Id[20];
-        int Math;
-        int Chinese;
-        int English;
-        int Sum;
-};
-
-int main(int argc, char const *argv[])
-{
-    char ch;
-    char Name[20],Id[20];
-    int Math,Chinese,English;
-    fstream ioFile;
-    ioFile.open("d:/per.dat",ios::out|ios::app);
-    cout<<"---------建立学生档案信息----------\n";
-    do{
-        cout<<"请输入姓名：";
-        cin>>Name;
-        cout<<"请输入身份证号：";
-        cin>>Id;
-        cout<<"请输入数学成绩：";
-        cin>>Math;
-        cout<<"请输入汉语成绩：";
-        cin>>Chinese;
-        cout<<"请输入英语成绩：";
-        cin>>English;
-        Person per(Name,Id,Math,Chinese,English);
-        ioFile.write((char *)&per,sizeof(per));
-        cout<<"您是否继续建档？(Y/y)  ";
-        cin>>ch;
-    }while(ch=='y'||ch=='Y');
-    ioFile.close();
-    ioFile.open("d://per.dat",ios::in);
-    Person p;
-    ioFile.read((char*)&p,sizeof(p));
-    vector<Person> v;
-    vector<Person>::iterator vt;
-    while(!ioFile.eof()){
-        v.push_back(p);
-        ioFile.read((char*)&p,sizeof(p));
-    }
-    ioFile.close();
-    cout<<"---------输出档案信息-----------"<<endl;
-    for(vt=v.begin();vt!=v.end();vt++){
-        (*vt).display();
-    }
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/输入输出运算符重载.cpp
+++ b/practical_exercises/key_exercises/输入输出运算符重载.cpp
@@ -1,41 +0,0 @@
-/*
-   有一销售人员类Sales，其数据成员有姓名name，身份证号id，年龄age。
-   重载输入/输出运算符实现对Sales类数据成员的输入和输出。
- */
-#include<iostream>
-#include<cstring>
-using namespace std;
-class Sales{
-        private:
-                char name[10];
-                char id[18];
-                int age;
-        public:
-                Sales(char *Name,char *ID,int Age);
-
-                friend  Sales &operator<<(ostream &os,Sales &s);        //重载输出运算符
-                friend  Sales &operator>>(istream &is,Sales &s);        //重载输入运算符
-};
-Sales::Sales(char *Name,char *ID,int Age) {
-        strcpy(name,Name);
-        strcpy(id,ID);
-        age=Age;
-}
-Sales& operator<<(ostream &os,Sales &s) {
-        os<<s.name<<"\t";                                       //输出姓名
-        os<<s.id<<"\t";                                         //输出身份证号
-        os<<s.age<<endl;                                        //输出年龄
-        return s;
-}
-Sales &operator>>(istream &is,Sales &s) {
-        cout<<"输入雇员的姓名，身份证号，年龄"<<endl;
-        is>>s.name>>s.id>>s.age;
-        return s;
-}
-int main(){
-        Sales s1("杜康","214198012111711",40);                  //L1
-        cout<<s1;                                               //L2
-        cout<<endl;                                                     //L3
-        cin>>s1;                                                        //L4
-        cout<<s1;                                                       //L5
-}
--- a/practical_exercises/key_exercises/输入输出重载.cpp
+++ b/practical_exercises/key_exercises/输入输出重载.cpp
@@ -1,41 +0,0 @@
-#include<iostream>
-using namespace std;
-#include<cstring>
-class Sales{
-private:
-    char name[10];
-    char id[18];
-    int age;
-public:
-    Sales(char *Name,char *ID,int Age);
-    friend Sales &operator<<(ostream &os,Sales &s);
-    friend Sales &operator>>(istream &is,Sales &s);
-
-};
-
-
-Sales::Sales(char *Name,char *ID,int Age){
-    strcpy(name,Name);
-    strcpy(id,ID);
-    age=Age;
-}
-
-Sales &operator<<(ostream&os,Sales &s){
-    os<<s.name<<"\t"<<s.id<<"\t"<<s.age<<endl;
-    return s;
-}
-
-Sales &operator>>(istream&is,Sales &s){
-    cout<<"输入雇员的姓名，身份证，年龄：\n";
-    is>>s.name>>s.id>>s.age;
-}
-
-int main(int argc, char const *argv[])
-{
-    Sales s("张三","15611",26);
-    cout<<s;
-    cin>>s;
-    cout<<s;
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/输出格式.cpp
+++ b/practical_exercises/key_exercises/输出格式.cpp
@@ -1,19 +0,0 @@
-#include<iostream>
-#include<iomanip>
-using namespace std;
-
-int main(int argc, char const *argv[])
-{
-    char s[20]="this is a string";
-    double digit=-36.96656;
-    cout<<setw(30)<<left<<setfill('*')<<s<<endl;
-    cout<<dec<<setprecision(4)<<digit<<endl;
-    cout<<dec<<15<<endl;
-    //setbase(int x)设置进制后，后面所有操作都是按照这个进制来计算！
-    cout<<setbase(10)<<15<<endl;
-    //四舍五入,并保留2位有效数组
-    float x=6.6937;
-    cout<<float(int(x*1000+0.5)/1000.0)<<endl;
-    system("pause");
-    return 0;
-}
--- a/practical_exercises/key_exercises/运算符重载之强制转换.cpp
+++ b/practical_exercises/key_exercises/运算符重载之强制转换.cpp
@@ -1,35 +0,0 @@
-/*
-有一个类Circle，设计该类的类型转换函数，当将Circle对象转换成int型时，返回圆的半径；当将它转换成double型时，就返回圆的周长；当将它转换成float型时，就返回圆的面积。
-*/
-
-/*
-
-类型转换函数没有参数。
-类型转换函数没有返回类型。
-类型转换函数必须返回将要转换成的type类型数据。
-
-*/
-
-#include <iostream>
-using namespace std;
-class Circle{
-private:
-    double x,y,r;
-public:
-    Circle(double x1,double y1,double r1){x=x1;y=y1;r=r1;	}
-    operator int(){return int(r);}
-    operator double(){return 2*3.14*r;}
-    operator float(){return (float)3.14*r*r;}
-};
-int main(){
-    Circle c(2.3,3.4,2.5);
-    int r=c;        //调用operator int()，将Circle类型转换成int
-    double length=c;   //调用operator double()，转换成double
-    float area=c;   //调用operator float()，将Circle类型转换成float
-    double len=(double) c;	//将Cirlce类型对象强制转换成double
-    cout<<r<<endl;
-    cout<<length<<endl;
-    cout<<len<<endl;
-    cout<<area<<endl;
-    system("pause");
-}
--- a/practical_exercises/key_exercises/重载圆括号的时钟.cpp
+++ b/practical_exercises/key_exercises/重载圆括号的时钟.cpp
@@ -1,25 +0,0 @@
-#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");
-}