四、实验内容
1.实验任务1
//在C++中定义和使用类模板
task1_1.cpp
#include <iostream>
using namespace std;
// 类A的定义
class A{
public:
A(int x0, int y0): x{ x0 }, y{ y0 } {}
void show() const { cout << x << ", " << y << endl; }
private:
int x, y;
};
// 类B的定义
class B{
public:
B(double x0, double y0): x{ x0 }, y{ y0 } {}
void show() const { cout << x << ", " << y << endl;}
private:
double x, y;
};
void test() {
cout << "测试类A: " << endl;
A a(3, 4);
a.show();
cout << "\n测试类B: " << endl;
B b(3.2, 5.6);
b.show();
}
int main() {
test();
}
运行结果：
task1_2.cpp
#include <iostream>
#include <string>
using namespace std;
// 定义类模板X
template<typename T>
class X{
public:
X(T x0, T y0): x{x0}, y{y0} {}
void show() const { cout << x << ", " << y << endl;}
private:
T x, y;
};
void test() {
cout << "测试1: 模板类抽象类型T用int实例化" << endl;
X<int> x1(3, 4);
x1.show();
cout << "\n测试2: 模板类抽象类型T用double实例化" << endl;
X<double> x2(3.2, 5.6);
x2.show();
cout << "\n测试3: 模板类抽象类型T用标准库中的string实例化" << endl;
X<std::string> x3("hello", "c plus plus");
x3.show();
}
int main() {
test();
}
运行结果：
2.实验任务2
//string类的部分使用方法
task2_1.cpp
#include <iostream>
#include <string>
#include <limits>
using namespace std;
int main() {
const int n = 10;
string prompt = string(n, '*') + "Enter a string: " + string(n, '*') + '\n';
cout << "测试1:";
cout << prompt;
string s1;
cin >> s1; // 从输入流中提取字符串给s1，碰到空格、回车、Tab键即结束
cout << "s1: " << s1 << endl;
cin.ignore(numeric_limits<streamsize>::max(), '\n'); // 清空输入缓冲区
cout << "\n测试2:";
cout << prompt;
getline(cin, s1); // 从输入流中提取一行字符串给s1，直到换行
cout << "s1: " << s1 << endl;
cout << "\n测试3:";
string s2, s3;
cout << prompt;
getline(cin, s2, ' '); // 从输入流中提取字符串给s2，直到指定分隔符空格
getline(cin, s3);
cout << "s2: " << s2 << endl;
cout << "s3: " << s3 << endl;
}
运行结果：
task2_2.cpp
#include <iostream>
#include <string>
int main() {
using namespace std;
string s;
cout << "Enter words: \n";
// 重复录入字符串，将小写字符转换成大写，直到按下Ctrl+Z
while( getline(cin, s) ) {
for(auto &ch: s)
ch = toupper(ch);
cout << s << "\n";
}
}
运行结果：
task2_3.cpp
#include <iostream>
#include <string>
#include <algorithm>
int main() {
using namespace std;
string s1;
cout << "Enter words: \n";
getline(cin, s1);
cout << "original words: \n";
cout << s1 <<endl;
cout << "to uppercase: \n";
transform(s1.begin(), s1.end(), s1.begin(), ::toupper);
cout << s1 << endl;
}
运行结果：
task2_4.cpp
#include <iostream>
#include <string>
int main() {
using namespace std;
string s1, s2;
s1 = "nuist"; // 赋值
s1[0] = 'N'; // 支持通过[]和索引方式访问
s1.at(1) = 'U'; // 支持通过xx.at()方法访问
cout << boolalpha << (s1 == "nuist") << endl; // 字符串比较
cout << s1.length() << endl; // 字符串长度
cout << s1.size() << endl; // 字符串长度
s2 = s1 + ", 2050"; // 字符串连接
cout << s2 << endl;
string email{"xyz@gmail.com"};
auto pos = email.find("@"); // 查找子串"@"第一次出现的索引位置，如果失败，返回string::npos
if (pos == string::npos)
cout << "illegal email address";
else {
auto s1 = email.substr(0, pos); // 取子串, 从索引0 ~ pos-1
auto s2 = email.substr(pos + 1); // 取子串，从pos+1到末尾
cout << s1 << endl;
cout << s2 << endl;
}
string phone{"15216982937"};
cout << phone.replace(3, 5, string(5, '*')) << endl; // 把从索引位置为3开始的连续5个字符替换成*
string s3{"cosmos"}, s4{"galaxy"};
cout << "s3: " + s3 + " s4: " + s4 << endl;
s3.swap(s4); // 交换
cout << "s3: " + s3 + " s4: " + s4 << endl;
string s5{"abc"};
const char *pstr = s5.c_str(); // 方法c_str()把string类字符串组转换成C风格的字符串
cout << pstr << endl;
string s6{"12306"};
int x1 = stoi(s6); // 把string转换成int
cout << x1 << endl;
int x2 = 12306;
string s7 = to_string(x2); // 把int转换成string
cout << s7 << endl;
double x3 = 123.06;
string s8 = to_string(x3); // 把double转换成string
cout << s8 << endl;
}
运行结果：
3.实验任务3
//动态数组类模板vector的基础用法
task3_1.cpp
#include <iostream>
#include <vector>
using namespace std;
template<typename T>
void output(const T &obj) {
for(auto &item: obj)
cout << item << ", ";
cout << "\b\b \n";
}
int main() {
vector<int> v1; // 创建一个vector对象v1, 未指定大小, 元素是int型, 未初始化
vector<int> v2(5); // 创建一个vector对象v2, 包含5个元素，元素是int型，初始值是默认值0
vector<int> v3(5, 42); // 创建一个vector对象v3, 包含5个元素，元素是int型，指定初始值是42
vector<int> v4{1, 9, 8, 4}; // 创建一个vector对象v4, 元素是int型，使用初始化列表方式
vector<int> v5{v4}; // 创建一个vector对象v5, 使用已经存在的对象v4创建
cout << "v2: ";
output(v2);
cout << "v3: ";
output(v3);
cout << "v4: ";
output(v4);
cout << "v5: ";
output(v5);
}
运行结果：
task3_2.cpp
#include <iostream>
#include <vector>
using namespace std;
void output(const vector<int> &v) {
cout << "v.size() = " << v.size() << endl;
cout << "v.capacity() = " << v.capacity() << endl;
cout << endl;
}
int main() {
vector<int> v{42};
output(v);
v.push_back(55);
v.push_back(90);
output(v);
for(auto i = 0; i < 8; ++i)
v.push_back(i);
output(v);
v.pop_back();
output(v);
}
运行结果：
4.实验任务4
//C++标准模板库中序列容器、迭代器在数据存储、访问/操作的通用处理方式
task4.cpp
#include <iostream>
#include <vector>
#include <array>
#include <string>
#include <algorithm>
using namespace std;
// 函数模板
// 通过索引方式输出对象值
template<typename T>
void output1(const T &obj) {
for(auto i = 0; i < obj.size(); ++i)
cout << obj.at(i) << ", ";
cout << "\b\b \n";
}
// 函数模板
// 通过迭代器方式输出对象值
template<typename T>
void output2(const T &obj) {
for(auto p = obj.cbegin(); p != obj.cend(); ++p)
cout << *p << ", ";
cout << "\b\b \n";
}
// 函数模板
// 通过auto for方式输出对象值
template<typename T>
void output3(const T &obj) {
for(auto &item: obj)
cout << item << ", ";
cout << "\b\b \n";
}
// 测试string类对象
void test1() {
string s1{"cplus"};
output1(s1);
reverse(s1.begin(), s1.end()); // 对对象s1中的数据项进行翻转
output2(s1);
sort(s1.begin(), s1.end()); // 对对象s1中的数据项排序(默认升序)
output3(s1);
}
// 测试array<int>类对象
void test2() {
array< array<int, 4>, 3> x{1, 9, 8, 4, 2, 0, 2, 3, 2, 0, 4, 9 };
output1( x.at(0) );
output2( x.at(1) );
output3( x.at(2) );
}
// 测试vector<string>类对象
void test3() {
vector<string> v1 {"Sheldon", "Leonard", "Howard", "Raj"};
v1.push_back("Penny");
v1.push_back("Amy");
output1(v1);
sort(v1.begin(), v1.end(), std::greater<string>()); // 对v1对象中的字符串按降序排序
output2(v1);
reverse(v1.begin(), v1.end()); // 对v1对象中的字符串翻转
output3(v1);
}
int main() {
cout << "测试1: " << endl;
test1();
cout << "测试2: " << endl;
test2();
cout << "测试3: " << endl;
test3();
}
运行结果：
5.实验任务5
textcoder.hpp
#pragma once
#include<iostream>
#include<string>
using namespace std;
class TextCoder {
public:
TextCoder(const string& s);
string getText() const;
string get_ciphertext();
string get_deciphertext();
private:
string text;
void encoder();
void decoder();
};
TextCoder::TextCoder(const string& s) : text(s) {}
string TextCoder::getText() const {
return text;
}
string TextCoder::get_ciphertext() {
encoder();
return text;
}
string TextCoder::get_deciphertext() {
decoder();
return text;
}
void TextCoder::encoder() {
for (char& ch : text) {
if (isalpha(ch)) {
char base = islower(ch) ? 'a' : 'A';
ch = (ch - base + 7) % 26 + base;
}
}
}
void TextCoder::decoder() {
for (char& ch : text) {
if (isalpha(ch)) {
char base = islower(ch) ? 'a' : 'A';
ch = (ch - base + 19) % 26 + base;
}
}
}
task5.cpp
#include "textcoder.hpp"
#include <iostream>
#include <string>
void test() {
using namespace std;
string text, encoded_text, decoded_text;
cout << "输入英文文本: ";
while (getline(cin, text)) {
encoded_text = TextCoder(text).get_ciphertext(); // 这里使用的是临时无名对象
cout << "加密后英文文本:\t" << encoded_text << endl;
decoded_text = TextCoder(encoded_text).get_deciphertext(); // 这里使用的是临时无名对象
cout << "解密后英文文本:\t" << decoded_text << endl;
cout << "\n输入英文文本: ";
}
}
int main() {
test();
}
运行结果：
6.实验任务6
Info.hpp
#pragma once
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
class Info {
public:
Info(const string& nickname, const string& contact, const string& city, int n);
void print() const;
private:
string nickname;
string contact;
string city;
int n;
};
Info::Info(const string& s1, const string& s2, const string& s3, int x) :nickname{ s1 }, contact{ s2 },
city{ s3 }, n{ x } {}
void Info::print() const {
cout << left << setw(15) << "昵称：" << nickname << endl;
cout << left << setw(15) << "联系方式：" << contact << endl;
cout << left << setw(15) << "所在城市：" << city << endl;
cout << left << setw(15) << "预定人数：" << n << endl;
cout << endl;
}
task6.cpp
#include "Info.hpp"
#include <iostream>
#include <vector>
#include<limits>
using namespace std;
const int capacity = 100;
void test() {
vector<Info> audience_info_list;
cout << "录入信息：\n\n";
string nickname, contact, city;
int n;
int N = 0;
while ( N <= capacity) {
// 录入信息
cout << "昵称：";
cin >> nickname;
if (cin.eof()) {
break; // Ctrl+Z 导致循环中止
}
cout << "联系方式（邮箱/手机号)：";
cin >> contact;
cout << "所在城市：";
cin >> city;
cout << "预定参加人数：";
cin >> n;
cout << endl;
if (cin.eof()) {
break; // Ctrl+Z 导致循环中止
}
N += n;
//判断预定参加人数是否超过livehouse场地剩余容量
if (N > capacity) {
N -= n;
int remain = capacity - N;
char choice;
cout << "对不起，只剩" << remain << "个位置。\n";
cout << "1.输入u，更新(update)预定信息\n";
cout << "2.输入q，退出预定\n";
cout << "你的选择：";
cin >> choice;
if (choice == 'q') {
cout << "退出预定。\n";
break;
}
else if (choice == 'u') {
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(), '\n');
cout << "请重新输入信息。\n";
continue;
}
}
audience_info_list.emplace_back(nickname, contact, city, n);
}
// 打印预约参加livehouse的听众信息
cout << "\n截至目前，一共有" << N << "位听众预定参加。预定听众信息如下：" << endl;
for (const auto& info : audience_info_list) {
info.print();
}
}
int main() {
test();
return 0;
}
运行结果1：
运行结果2：
六、实验总结
仍然有很多需要改进的地方，实验六的部分代码还可以进一步完善。希望在不断动手实践的过程中学习新的知识，多加以运用到今后实际代码的编写，加深记忆，学会真正运用。
标签：const,string,int,void,C++,实验,include,模板,cout From： https://www.cnblogs.com/Rainbow-forest/p/17868081.html