实验1 现代C++编程初体验

实验任务1：

Task1源代码：

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

template<typename T>
void output(const T &c);

void test1();
void test2();
void test3();

int main() {
    std::cout << "测试1: \n";
    test1();

    std::cout << "\n测试2: \n";
    test2();

    std::cout << "\n测试3: \n";
    test3();
}

template <typename T>
void output(const T &c) {
    for(auto &i : c)
        std::cout << i << ' ';
    std::cout << '\n';
}

void test1() {
    using namespace std;

    string s0{"0123456789"};
    cout << "s0 = " << s0 << endl;

    string s1(s0);
    reverse(s1.begin(), s1.end());
    cout << "s1 = " << s1 << endl;

    string s2(s0.size(), ' ');
    reverse_copy(s0.begin(), s0.end(), s2.begin());
    cout << "s2 = " << s2 << endl;
}

void test2() {
    using namespace std;

    vector<int> v0{2, 0, 4, 9};
    cout << "v0: "; output(v0);

    vector<int> v1{v0};
    reverse(v1.begin(), v1.end());
    cout << "v1: "; output(v1);

    vector<int> v2{v0};
    reverse_copy(v0.begin(), v0.end(), v2.begin());
    cout << "v2: "; output(v2);
}

void test3() {
    using namespace std;

    vector<int> v0{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    cout << "v0: "; output(v0);

    vector<int> v1{v0};
    rotate(v1.begin(), v1.begin()+1, v1.end());
    cout << "v1: "; output(v1);

    vector<int> v2{v0};
    rotate(v2.begin(), v2.begin()+2, v2.end());
    cout << "v2: "; output(v2);

    vector<int> v3{v0};
    rotate(v3.begin(), v3.end()-1, v3.end());
    cout << "v3: "; output(v3);

    vector<int> v4{v0};
    rotate(v4.begin(), v4.end()-2, v4.end());
    cout << "v4: "; output(v4);
}

运行结果截图：

观察与思考：

reserve：直接反转原容器中的元素顺序，原容器会被修改。

reverse_copy：不修改原容器，将原容器的反转结果拷贝到新容器。

rotate 通过将 middle 指向的元素作为新起始，把其之前的元素移到区间末尾来改变顺序。三个参数分别控制旋转区间的起始、新起点和结束位置。

实验任务2：

Task2源代码：

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <iomanip>
#include <cstdlib>
#include <ctime>

template<typename T>
void output(const T &c);

int generate_random_number();
void test1();
void test2();

int main() {
    std::srand(std::time(0));  
    std::cout << "测试1: \n";
    test1();

    std::cout << "\n测试2: \n";
    test2();
}

template <typename T>
void output(const T &c) {
    for(auto &i : c) {
        std::cout << i << ' ';
    }
    std::cout << '\n';
}

int generate_random_number() {
    return std::rand() % 101;
}

void test1() {
    using namespace std;

    vector<int> v0(10); 
    generate(v0.begin(), v0.end(), generate_random_number); 
    cout << "v0: "; output(v0);

    vector<int> v1{v0};
    sort(v1.begin(), v1.end()); 
    cout << "v1: "; output(v1);

    vector<int> v2{v0};
    sort(v2.begin()+1, v2.end()-1); 
    cout << "v2: "; output(v2);
}

void test2() {
    using namespace std;

    vector<int> v0(10);
    generate(v0.begin(), v0.end(), generate_random_number);
    cout << "v0: "; output(v0);


    auto min_iter = min_element(v0.begin(), v0.end());
    auto max_iter = max_element(v0.begin(), v0.end());
    cout << "最小值: " << *min_iter << endl;
    cout << "最大值: " << *max_iter << endl;

    auto ans = minmax_element(v0.begin(), v0.end());
    cout << "最小值: " << *(ans.first) << endl;
    cout << "最大值: " << *(ans.second) << endl;

    double avg1 = accumulate(v0.begin(), v0.end(), 0.0) / v0.size();
    cout << "均值: " << fixed << setprecision(2) << avg1 << endl;

    sort(v0.begin(), v0.end());
    double avg2 = accumulate(v0.begin()+1, v0.end()-1, 0.0) / (v0.size()-2);
    cout << "去掉最大值、最小值之后，均值: " << avg2 << endl;
}

运行结果截图：

观察与思考：

generate 算法的作用：通过调用指定的生成函数，为容器的指定迭代器区间内的元素赋值，实现批量生成数据填充容器。

minmax_element 的优势：只需一次遍历容器，就能同时获取最小值和最大值的迭代器，效率更高。

效果等同，Lambda表达式是C++匿名函数，格式为 [捕获列表](参数列表){函数体} ，此处 []() {return std::rand()%101;} 无捕获、无参数，返回随机数，与原函数功能一致。

实验任务3：

Task3源代码：

#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>

unsigned char func(unsigned char c);
void test1();
void test2();

int main() {
    std::cout << "测试1：字符串大小写转换\n";
    test1();

    std::cout << "\n测试2：字符变换\n";
    test2();

    return 0;
}

unsigned char func(unsigned char c) {
    if(c == 'z')
        return 'a';
    if(c == 'Z')
        return 'A';
    if(std::isalpha(c))
        return static_cast<unsigned char>(c+1);
    return c;
}

void test1() {
    std::string s1{"Hello world 2049!"};
    std::cout << "s1 = " << s1 << '\n';

    std::string s2;
    for(auto c : s1)
        s2 += std::tolower(c);
    std::cout << "s2 = " << s2 << '\n';

    std::string s3;
    for(auto c : s1)
        s3 += std::toupper(c);
    std::cout << "s3 = " << s3 << '\n';
}

void test2() {
    std::string s1{"I love cosmos!"};
    std::cout << "s1 = " << s1 << '\n';

    std::string s2(s1.size(), ' ');
    std::transform(s1.begin(), s1.end(),
                   s2.begin(),
                   func);
    std::cout << "s2 = " << s2 << '\n';
}

运行结果截图：

观察与思考：

自定义函数 func ：将 'z' 转为 'a' ， 'Z' 转为 'A' ，其他字母按字母表后移一位，非字母字符保持不变。

tolower ：将大写字母转换为小写字母； toupper ：将小写字母转换为大写字

transform 的4个参数：前两个参数指定源区间的起始和结束迭代器，第三个参数指定目标区间的起始迭代器，第四个参数是变换函数。

若把第三个参数 s2.begin() 改成 s1.begin() ，会直接在原字符串 s1 上进行变换，覆盖原有内容，而原本是将结果存入 s2 ，两者存储目标不同。

实验任务4：

Task4源代码：

#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>

bool is_palindrome(const std::string &s);
bool is_palindrome_ignore_case(const std::string &s);

int main() {
    using namespace std;
    string s;

    // 多组输入，直到按下Ctrl+Z结束测试
    while (cin >> s) {
        cout << boolalpha
             << "区分大小写: " << is_palindrome(s) << "\n"
             << "不区分大小写: " << is_palindrome_ignore_case(s) << "\n\n";
    }
}

// 函数is_palindrome定义：严格区分大小写判断回文
bool is_palindrome(const std::string &s) {
    int left = 0;
    int right = s.size() - 1;
    while (left < right) {
        if (s[left] != s[right]) {
            return false;
        }
        left++;
        right--;
    }
    return true;
}

// 函数is_palindrome_ignore_case定义：不区分大小写判断回文
bool is_palindrome_ignore_case(const std::string &s) {
    int left = 0;
    int right = s.size() - 1;
    while (left < right) {
        if (std::tolower(s[left]) != std::tolower(s[right])) {
            return false;
        }
        left++;
        right--;
    }
    return true;
}

运行结果截图：

观察与思考：

可以将输入方式从 cin >> s 改为 std::getline(cin, s) 。 std::getline 会读取一整行输入，包括其中的空格，直到遇到换行符为止。

实验任务5：

Task5源代码：

#include <iostream>
#include <string>
#include <algorithm>

std::string dec2n(int x, int n = 2);

int main() {
    int x;
    while (std::cin >> x) {
        std::cout << "十进制：" << x << '\n'
                  << "二进制：" << dec2n(x) << '\n'
                  << "八进制：" << dec2n(x, 8) << '\n'
                  << "十二进制：" << dec2n(x, 12) << '\n'
                  << "十六进制：" << dec2n(x, 16) << '\n'
                  << "三十二进制：" << dec2n(x, 32) << "\n\n";
    }
}

std::string dec2n(int x, int n) {
    if (x == 0) {
        return "0";
    }
    std::string result;
    while (x > 0) {
        int mod = x % n;
        char ch = (mod < 10) ? ('0' + mod) : ('A' + (mod - 10));
        result += ch; 
        x = x / n;
    }
    std::reverse(result.begin(), result.end());
    return result;
}

运行结果截图：

实验任务6：

Task6源代码：

#include <iostream>
#include <string>
#include <vector>
#include <iomanip>

class CipherTable {
private:
    std::vector<std::string> rows;  

public:
    CipherTable() {
        generateTable();  
    }

    void generateTable() {
        std::string lowercaseBase = "abcdefghijklmnopqrstuvwxyz";
        std::string uppercaseBase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        std::string spacedLower;
        for (char c : lowercaseBase) {
            spacedLower += c;
            spacedLower += " ";
        }
        rows.push_back(spacedLower);

        for (int i = 1; i <= 25; ++i) {
            std::string shifted = uppercaseBase.substr(i) + uppercaseBase.substr(0, i);
            std::string spacedShifted;
            for (char c : shifted) {
                spacedShifted += c;
                spacedShifted += " ";
            }
            rows.push_back(spacedShifted);
        }

        std::string spacedUpper;
        for (char c : uppercaseBase) {
            spacedUpper += c;
            spacedUpper += " ";
        }
        rows.push_back(spacedUpper);
    }

    void print() {
        for (size_t i = 0; i < rows.size(); ++i) {
            if (i == 0) {
                std::cout << "  " << rows[i] << std::endl;
            } else {
                std::cout << std::setw(2) << i << " " << rows[i] << std::endl;
            }
        }
    }
};

int main() {
    CipherTable table;
    table.print();
    return 0;
}

运行结果截图：

实验任务7：

Task7源代码：

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <iomanip>

class ArithmeticQuiz {
private:
    int correctCount; 
    int totalCount;   

public:
    ArithmeticQuiz() : correctCount(0), totalCount(10) {}

    int generateRandomNumber(int min, int max) {
        return rand() % (max - min + 1) + min;
    }

    void generateAndEvaluateQuestion() {
        int num1 = generateRandomNumber(1, 10);
        int num2 = generateRandomNumber(1, 10);
        char op;

        int opChoice = generateRandomNumber(1, 4);
        switch (opChoice) {
            case 1:
                op = '+';
                break;
            case 2:
                op = '-';
                if (num1 < num2) {
                    std::swap(num1, num2);
                }
                break;
            case 3:
                op = '*';
                break;
            case 4:
                op = '/';
                while (num2 == 0 || num1 % num2 != 0) {
                    num1 = generateRandomNumber(1, 10);
                    num2 = generateRandomNumber(1, 10);
                }
                break;
        }

        int correctAnswer;
        switch (op) {
            case '+':
                correctAnswer = num1 + num2;
                break;
            case '-':
                correctAnswer = num1 - num2;
                break;
            case '*':
                correctAnswer = num1 * num2;
                break;
            case '/':
                correctAnswer = num1 / num2;
                break;
            default:
                correctAnswer = 0;
        }

        std::cout << num1 << " " << op << " " << num2 << " = ";
        int userAnswer;
        std::cin >> userAnswer;

        if (userAnswer == correctAnswer) {
            correctCount++;
        }
    }

    void runTest() {
        srand(static_cast<unsigned int>(time(0))); 

        for (int i = 0; i < totalCount; i++) {
            generateAndEvaluateQuestion();
        }

        double accuracy = static_cast<double>(correctCount) / totalCount * 100;
        std::cout << "正确率: " << std::fixed << std::setprecision(2) << accuracy << "%" << std::endl;
    }
};

int main() {
    ArithmeticQuiz quiz;
    quiz.runTest();
    return 0;
}

运行结果截图：

posted @ 2025-10-17 16:27 Coisini12 阅读(6) 评论(1) 收藏举报

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实验1 现代C++编程初体验

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