实验任务3 Complex类的自我实现
简要说明：不使用C++标准库，自行设计并实现一个复数类Complex，并满足简单的使用需求。
程序包括 Complex.hpp与 task3.cpp 。
Complex.hpp：
1 #ifndef COMPLEX_HPP
2 #define COMPLEX_HPP
3 #include<iostream>
4 #include <math.h>
5
6
7 class Complex
8
9 {
10 public:
11 Complex() {};
12
13 Complex(double a0, double b0 = 0) :a(a0), b(b0) {}
14
15 Complex(const Complex& p) :a(p.a), b(p.b) {}
16
17 ~Complex() = default;
18
19 double get_real() const { return a; }
20 double get_imag() const { return b; }
21
22 void show() const {
23 std::cout << a;
24 if (b > 0) { std::cout << "+" << b << "i"; }
25 else if(b<0) std::cout << b << "i" << std::endl;
26
27 }
28
29 void add(const Complex& p) { a += p.a; b += p.b; }
30
31 friend Complex add (const Complex& p1, const Complex& p2);//用于实现两个复数相加，返回复数。
32 friend bool is_equal (const Complex& p1,const Complex& p2);//用于判断两个复数是否相等，返回true/false。
33 friend double abs (const Complex& p);//用于对复数进行取模运算。
34
35 private:
36 double a, b;
37 };
38
39 Complex add(const Complex& p1, const Complex& p2) {
40
41 Complex kk;
42 kk.a = p1.a + p2.a;
43 kk.b = p1.b + p2.b;
44
45 return kk;
46 }
47
48 bool is_equal(const Complex& p1, const Complex& p2) {
49
50 if (p1.a == p1.a && p1.b == p2.b) return true; else return false;
51
52 }
53
54 double abs(const Complex& p) {
55
56 double m = p.a, n = p.b;
57
58 return sqrt(m * m + n * n);
59
60 }
61 #endif
task3.cpp：
1 #include "Complex.hpp"
2 #include <iostream>
3 int main()
4 {
5 using namespace std;
6
7 Complex c1(4, -3);
8 const Complex c2(2.5);
9 Complex c3(c1);
10
11 cout << "c1 = ";
12 c1.show();
13 cout << endl;
14
15 cout << "c2 = ";
16 c2.show();
17 cout << endl;
18 cout << "c2.imag = " << c2.get_imag() << endl;
19
20 cout << "c3 = ";
21 c3.show();
22 cout << endl;
23
24 cout << "abs(c1) = ";
25 cout << abs(c1) << endl;
26
27 cout << boolalpha;
28 cout << "c1 == c3 : " << is_equal(c1, c3) << endl;
29 cout << "c1 == c2 : " << is_equal(c1, c2) << endl;
30
31 Complex c4;
32 c4 = add(c1, c2);
33 cout << "c4 = c1 + c2 = ";
34 c4.show();
35 cout << endl;
36
37 c1.add(c2);
38 cout << "c1 += c2, " << "c1 = ";
39 c1.show();
40 cout << endl;
41 }
更改数据后的测试结果：
实验任务4 设计并实现一个用户类User。
程序包括 User.hpp与 task4.cpp 。
User.hpp:
1 #ifndef USER_HPP
2 #define USER_HPP
3
4 // Employee类的定义
5 #include <iostream>
6 #include <string>
7 using std::cin;
8 using std::cout;
9 using std::endl;
10 using std::string;
11 class User {
12 public:
13 User(string name0, string passwd0 = "111111", string email0 = "") :name(name0), passwd(passwd0), email(email0) { n++; };
14 ~User() {};
15 void set_email();
16 void change_passwd();
17 void print_info();
18 static void print_n(){ cout << "there are" << n << " users."; }
19 private:
20 string name, passwd, email;
21 static int n;
22
23 };
24 int User::n = 0;
25 void User::set_email() {
26 cout << "Enter email address: ";
27 cin >> email;
28 size_t position;
29 position = email.find("@");
30 while(position == string::npos){ //检测邮箱地址是否包含@
31 cout << "The email should inculde '@'." << endl;
32 cout << "Please re-enter again: ";
33 cin >> email;
34 position = email.find("@");
35 }
36 cout << "email is set successfully..." << endl;
37 }
38 void User::change_passwd() {
39 int i = 0;
40 string newpasswd;
41 cout << "Enter old password: ";
42 while (i < 3) {
43 cin >> newpasswd;
44 if (passwd == newpasswd) {
45 cout << "Enter new passwd: ";
46 int a;
47 do { //保证密码长度必须>=6
48
49 cin >> passwd;
50 a = passwd.length();
51 if (a < 6) {
52 cout << "password lengh must be more than 5 numbers." << endl;
53 cout << "Please re-enter again: ";
54 }
55 } while (a < 6);
56 cout << "new passwd is set succeddfully..." << endl;
57 break;
58 }
59 else {
60 i++;
61 if (i < 3)
62 cout << "password input error. Please re-enter again: ";
63 else if (i == 3)cout << "password input error. Please try after a while." << endl;
64
65 }
66
67 }
68 }
69 void User::print_info() {
70 cout << "name: " << name << endl;
71 cout << "passwd: ******" << endl;
72 cout << "email: " << email << endl;
73 }
74 #endif
task4.cpp：
1 #include "User.hpp"
2 #include <iostream>
3
4 int main()
5 {
6 using namespace std;
7
8 cout << "testing 1......" << endl;
9 User user1("Jonny", "123456", "xyz@hotmail.com");
10 user1.print_info();
11
12 cout << endl
13 << "testing 2......" << endl
14 << endl;
15 User user2("Leonard");
16 user2.change_passwd();
17 user2.set_email();
18 user2.print_info();
19
20 User::print_n();
21 }
实验总结：
1.hpp和cpp文件要保存在相同的路径，才能编译成功。
2.class的定义时结尾处要有结束符“；”。
3.对于减少using namespace std影响的几个办法：
a.直接在函数名前加上std::
b.
直接把using的作用域限制到一个函数中，例如：
void temp()
{
using namespace std;
cout<<"kk"<<endl;
}
c.在开头写出using std::+需要用的函数名;
4.string类中find函数返回的值npos因为是无符号整型，所以相对方便的办法是直接和npos作比较。