实验一
Task 1
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());
string s2(s0.size(), ' ');
reverse_csigny(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_csigny(v0.begin(), v0.end(), v2.begin());
cout << "v1: ";
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);
}
测试截图
问题
问题一
reverse()函数会修改原容器，直接进行反转的过程
reverse_csigny()函数不修改原容器，在反转操作之后直接复制到指定的容器中
问题二
rotate算法的原型是rotate(begin, mid , end)
(1)将[begin,end)范围内的元素进行循环旋转，使得mid位置的元素成为新的第一个元素
(2) begin:范围的开始（包含）
mid:该位置的元素成为新的首元素
end:范围的结束（不包含）
Task 2
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() {
//添加随机种子
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 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;
}
测试截图
问题
问题一
generate()函数原型为generate(begin,end,value)，作用是将begin到end的部分用vale值填充全部
问题二
minmax_element()函数比max_element()和min_element()函数加起来调用的时间更少，并且书写代码更少
问题三
可以替换，作用与generate_random_number()函数完全等同
Task 3
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();
}
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;
//转化为全小写字符串
for (auto c : s1)
s2 += std::tolower(c);
std::cout << "s2 = " << s2 << '\n';
std::string s3;
//转化为全大写字符串
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';
}
测试截图
问题
问题一
将小写和大写字母表循环，将字符替换为顺序表中的下一个（如a变成b，z变成a）
问题二
tolower()将字符串中的所有字符变成小写字符，符号数字除外
toupper()将字符串中的所有字符变成大写字符，符号数字除外
问题三
(1)将从s1.begin()到s1.end()的字符串用func()函数，将结果返回到以s2.begin()开始的字符串中
(2)修改后结果会直接返回在s1上，即s1会被改变
Task 4
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";
}
}
bool is_palindrome(const std::string& s) {
std::string s0(s);
reverse(s0.begin(), s0.end());
for (auto i : s) {
if (s != s0)
return false;
}
return true;
}
bool is_palindrome_ignore_case(const std::string& s) {
std::string s1,s2;
for (auto c : s) {
s1 +=std::tolower(c);
s2 += std::tolower(c);
}
reverse(s2.begin(), s2.end());
for (auto i : s) {
if (s1 != s2)
return false;
}
return true;
}
测试截图
问题
用getline()函数代替cin，代码如下：
//将原文件第12行替换为：
while (getline(cin, s)) {
if (s.empty()) {
break;
}
Task 5
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";
}
const std::string basic = "0123456789ABCDEFGHIJKLMNsignQRSTUVWXYZ";
std::string result;
while (x > 0) {
int remainder = x % n;
result += basic[remainder];
x = x / n;
}
std::reverse(result.begin(), result.end());
return result;
}
测试截图
Task 6
源代码
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
int main() {
std::string v0{"abcdefghijklmnsignqrstuvwxyz"};
std::string s;
for (auto c : v0)
s += std::toupper(c);
std::cout << " ";
for (auto i : v0)
std::cout << " " << i;
std::cout << std::endl;
int i = 1;
for (i = 1; i <= 26; i++) {
if (i < 10)
std::cout << " " << i;
else
std::cout << i;
int index;
for (int j = 0; j < 26; j++) {
index = (i + j) % 26;
std::cout << " " << s[index];
}
std::cout << std::endl;
}
}
测试截图
Task 7
源代码
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
int main() {
std::srand(std::time(0));
int correctCount = 0;
for (int i = 0; i < 10; i++) {
int num1 = rand() % 10 + 1;
int num2 = rand() % 10 + 1;
int sign = rand() % 4;
int userAnswer, correctAnswer;
char signChar;
switch (sign) {
case 0:
signChar = '+';
correctAnswer = num1 + num2;
break;
case 1:
if (num1 < num2) {
swap(num1, num2);
}
signChar = '-';
correctAnswer = num1 - num2;
break;
case 2:
signChar = '*';
correctAnswer = num1 * num2;
break;
case 3:
while (num2 == 0 || num1 % num2 != 0) {
num1 = rand() % 10 + 1;
num2 = rand() % 10 + 1;
}
signChar = '/';
correctAnswer = num1 / num2;
break;
}
cout << num1 << " " << signChar << " " << num2 << " = ";
cin >> userAnswer;
if (userAnswer == correctAnswer) {
correctCount++;
}
}
double accuracy = static_cast<double>(correctCount) / 10 * 100;
cout << "正确率：" << accuracy << "%" << endl;
}
测试截图
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