实验1 现代C++编程初体验
实验任务一
#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); }
问题1：reverse修改原数据，reverse_copy创建反转副本且不改变原数据
问题2：rotate算法通过循环移位来改变元素顺序，first：区间起始位置，middle：新的起始位置（旋转中心点），last：区间结束位置
实验任务二
#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 << "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 max_it = max_element(v0.begin(), v0.end()); auto min_it = min_element(v0.begin(), v0.end()); cout << "最小值: " << *min_it << endl; cout << "最大值: " << *max_it << 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; }
问题1：用指定生成器函数的结果填充容器的某个区间
问题2：代码更简洁，访问更高效
问题3：相同
实验任务三
#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 << "测试2：字符替换\n"; test2(); } unsigned char func(unsigned char c) { if (c == '1') return 'a'; if (c == '2') return 'A'; if (std::isalpha(c)) return static_cast<unsigned char>(c + 1); return c; } void test1() { std::string s = "Hello World 2048!"; std::cout << "s = " << s << "\n"; std::string s1; for (char c : s) s1 += std::tolower(c); std::cout << "s1 = " << s1 << "\n"; std::string s2; for (char c : s) s2 += std::toupper(c); std::cout << "s2 = " << s2 << "\n"; } void test2() { std::string s1 = "I love C++!"; std::cout << "s1 = " << s1 << "\n"; std::string s2(s1.size(), '*'); std::transform(s1.begin(), s1.end(), s2.begin(), func); std::cout << "s2 = " << s2 << "\n"; }
问题1：主要功能是将字符串中的大写字母转换为小写字母，同时删除字符串中的所有数字字符
问题2：tolower：将大写字母转换为对应的小写字母；toupper：将小写字母转换为对应的大写字母
问题3：1：指定区域的起始位置，2：指定区域的结束位置，3：生成的数据开始存储的位置，4：数据转化/处理规则
实验任务四
#include <iostream> #include <string> #include <algorithm> #include <cctype> using namespace std; 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"; } } // 严格区分大小写的回文判断函数 bool is_palindrome(const std::string &s) { int left = 0; int right = s.length() - 1; while (left < right) { if (s[left] != s[right]) { return false; } left++; right--; } return true; } // 不区分大小写的回文判断函数 bool is_palindrome_ignore_case(const std::string &s) { int left = 0; int right = s.length() - 1; while (left < right) { // 将字符转换为小写后比较 if (tolower(s[left]) != tolower(s[right])) { return false; } left++; right--; } return true; }
问题1：使用getline()函数
int main() { string s; cout << "请输入字符串（可包含空格，空行退出）: " << endl; while (getline(cin, s)) { if (s.empty()) { // 输入空行时退出 break; }
实验任务五
#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){ std::string result ; char str ; if(x == 0){ return "0" ; } while(x>0){ int remainder = x % n ; if( remainder < 10 ){ str = '0' + remainder ; } else{ str = 'A' + remainder - 10 ; } result.insert(0 , 1, str) ; x = x/n ; } return result ; }
实验任务六
#include <iostream> #include <string> #include <algorithm> #include <iomanip> int main() { std::string start; for (int i = 0; i < 26; i++) { start += static_cast<char>(97 + i); } std::cout << " "; for (int i = 0; i < 26; i++) { std::cout << start[i] << " "; } std::cout << std::endl; for (int i = 1; i <= 26; i++) { std::cout << std::setw(2) << i << " "; std::rotate(start.begin(), start.begin() + 1, start.end()); for (int j = 0; j < 26; j++) { std::cout << static_cast<char>(toupper(start[j])) << " "; } std::cout << std::endl; } }
实验任务七
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <iomanip>
using namespace std;
int main() {
// 设置随机种子，确保每次运行题目不同
srand(time(0));
int correctCount = 0; // 正确答案计数
const int totalQuestions = 10; // 总题目数
cout << "=== 小学生算术运算测试 ===" << endl;
cout << "请回答以下10道算术题：" << endl << endl;
for (int i = 1; i <= totalQuestions; i++) {
// 生成两个1-10的随机操作数
int num1 = rand() % 10 + 1;
int num2 = rand() % 10 + 1;
// 随机选择运算符：0-加, 1-减, 2-乘, 3-除
int operation = rand() % 4;
char opChar;
int correctAnswer;
int userAnswer;
// 根据运算符类型处理题目
switch (operation) {
case 0: // 加法
opChar = '+';
correctAnswer = num1 + num2;
break;
case 1: // 减法（确保num1 >= num2）
if (num1 < num2) {
swap(num1, num2); // 交换确保第一个数大于等于第二个数
}
opChar = '-';
correctAnswer = num1 - num2;
break;
case 2: // 乘法
opChar = '*';
correctAnswer = num1 * num2;
break;
case 3: // 除法（确保能整除）
// 重新调整num2，确保num1能被num2整除
if (num1 % num2 != 0) {
// 找到num1的约数作为num2
for (int divisor = num1; divisor >= 1; divisor--) {
if (num1 % divisor == 0 && divisor <= 10) {
num2 = divisor;
break;
}
}
}
opChar = '/';
correctAnswer = num1 / num2;
break;
}
// 显示题目并获取用户答案
cout << "第" << setw(2) << i << "题: " << num1 << " " << opChar << " " << num2 << " = ";
cin >> userAnswer;
// 检查答案是否正确
if (userAnswer == correctAnswer) {
cout << "✓ 正确！" << endl;
correctCount++;
} else {
cout << "✗ 错误！正确答案是: " << correctAnswer << endl;
}
cout << endl;
}
// 计算并显示正确率
double accuracy = (static_cast<double>(correctCount) / totalQuestions) * 100;
cout << "=== 测试结果 ===" << endl;
cout << "答对题数: " << correctCount << "/" << totalQuestions << endl;
cout << fixed << setprecision(2);
cout << "正确率: " << accuracy << "%" << endl;
return 0;
}
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