任务1
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// 现代C++标准库、算法库体验
// 本例用到以下内容:
// 1. 字符串string, 动态数组容器类vector、迭代器
// 2. 算法库：反转元素次序、旋转元素
// 3. 函数模板、const引用作为形参
#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);
}
![屏幕截图 2026-10-20 105002]()
- 问题回答
1. reverse：原地反转区间元素，直接修改原容器。
reverse_copy：将区间元素反转后拷贝至另一容器，源容器不变。
2. rotate(first, middle, last)：原地旋转 [first,last) 区间；旋转后middle位置元素成为区间首元素。
参数： first 区间起点， middle 旋转分界点， last 区间尾后迭代器。
任务2
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#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <iomanip>
#include <cstdlib>
#include <ctime>
// 模板函数声明
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;
}
![屏幕截图 2026-10-20 105042]()
- 问题回答
1. generate：调用给定生成器，给区间内每个元素赋值。
2. minmax_element优势：只需遍历一遍容器，同时拿到最小、最大值；分开调用要遍历两次，效率更高。
3. 效果等同：lambda是匿名函数，这里等价于原来的 generate_random_number ，不用单独写命名函数。
任务3
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#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();
}
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';
}
![屏幕截图 2026-10-20 105117]()
- 问题回答
1. func：字母向后移1位， z 转为 a 、 Z 转为 A ，非字母字符保持不变。
2. tolower：字母转小写；toupper：字母转大写。
3. transform参数：
第1、2个：源区间起止迭代器 [first,last)
第3个：目标起始迭代器
第4个：转换函数改成 s1.begin() ：原地转换，直接修改原字符串 s1 ；原来写法是不改动源串，结果存入 s2 。
任务4
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#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
bool is_palindrome(const std::string &s) {
for (int i = 0; i < s.length()/2; i++)
{
if (s[i] != s[s.length() - 1 - i])
{
return false;
}
}
return true;
}
// 函数is_palindrome_ignore_case定义
bool is_palindrome_ignore_case(const std::string &s) {
for (int i = 0; i < s.length()/2; i++)
{
int m = tolower(s[i]);
int n = tolower(s[s.length() - 1 - i]);
if (m != n)
{
return false;
}
}
return true;
}
+ 程序运行截图
![屏幕截图 2026-10-20 112129]()
- 问题回答
将 cin >> s 改为 getline(cin, s) ， getline 读取一整行，包含空格，直到回车为止。
任务5
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#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";
}
}
// 函数dec2n定义
std::string dec2n(int x, int n) {
std::string num;
if (n <= 10)
{
while (x/n != 0)
{
num.push_back('0' + x%n);
x /= n;
}
num.push_back('0' + x);
} else {
while (x/n != 0)
{
if (x%n > 9)
{
num.push_back('A' + x%n-10);
x /= n;
} else {
num.push_back('0' + x%n);
x /= n;
}
}
if (x > 9)
{
num.push_back('A' + x - 10);
} else {
num.push_back('0' + x);
}
}
reverse(num.begin(), num.end());
return num;
}
![屏幕截图 2026-10-20 115429]()
任务6
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#include <iostream>
#include <iomanip>
int main() {
char str = 'a';
std::cout << " ";
while (str != 'z' + 1)
{
std::cout << str << " ";
str++;
}
std::cout << std::endl;
str = 'A' + 1;
for (int i = 1; i <= 26; i++)
{
std::cout << std::right << std::setw(2) << i << " ";
while (str != 'Z' + 1)
{
std::cout << str << " ";
str++;
}
str = 'A';
while (str != 'A' + i)
{
std::cout << str << " ";
str++;
}
std::cout << std::endl;
str++;
}
}
![屏幕截图 2026-10-20 125113]()
任务7
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#include <iostream>
#include <ctime>
#include <cstdlib>
#include <iomanip>
int generate_number();
int generate_result();
int main() {
double percent = 0;
for (int i = 0; i < 10; i++)
{
percent += generate_result();
}
percent = percent/10*100;
std::cout <<"正确率：" << std::fixed << std::setprecision(2) << percent << "%" << std::endl;
}
int generate_number() {
return std::rand() % 10 + 1;
}
int generate_result() {
srand(time(0));
int num = std::rand() % 4;
int i = 0;
int result;
int m = generate_number();
int n = generate_number();
switch (num)
{
case 0:
std::cout << m << " + " << n << " = ";
std::cin >> result;
if (m + n == result)
{
return 1;
} else {
return 0;
}
case 1:
if (m < n)
{
int t = m;
m = n;
n = t;
}
std::cout << m << " - " << n << " = ";
std::cin >> result;
if (result == m - n)
{
return 1;
} else {
return 0;
}
case 2:
std::cout << m << " * " << n << " = ";
std::cin >> result;
if (result == m * n)
{
return 1;
} else {
return 0;
}
default:
if (m > n && m % n != 0)
{
while (m % n != 0)
{
n--;
}
} else {
int t = m;
m = n;
n = t;
while (m % n != 0)
{
n--;
}
}
std::cout << m << " / " << n << " = ";
std::cin >> result;
if (result == m / n)
{
return 1;
} else {
return 0;
}
}
}
![屏幕截图 2026-10-20 135428]()
![屏幕截图 2026-10-20 135518]()
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