строки в стилях С и С++

#include <iostream>
#include <string>

using namespace std;

void work_with_string() {

    cout << "Hello world!" << endl;
    const char* str = "Hello world!";

    //char* str2 =  "Hi man";
    char str2[]{"Hi man"}; // 'H', 'i', ' ', 'm', 'a', 'n', '\0'
    cout << 'a' << "a" << endl;

    char* str3 = str2;
    char str5[]{ 'H', 'i', ' ', 'B', 'o', 'b' };

    // терминальный ноль.
    char str6[]{ 'H', 'i', ' ', 'B', 'o', 'b', '\0'};
    cout << str2 << endl;
    cout << str5 << endl;
    cout << str6 << endl;

    // Работаем как с обычными массивами
    cout << str[3] << " " << str[2] << endl;

    str2[3] = '@';
    cout << str2 << endl;


    //std::string
    string str4 = "Hi girl";


    // длинна строки
    cout << str2 << endl;
    cout << sizeof(str2) / sizeof(str2[0]) << endl;
    cout << strlen(str2) << endl;

    const int size_str2 = sizeof(str2) / sizeof(str2[0]);
    char deepcopy_str2[size_str2];
    for (int k = 0; k < size_str2; k++)
        deepcopy_str2[k] = str2[k];
    deepcopy_str2[0] = '$';
    cout << deepcopy_str2 << endl;
    cout << str2 << endl;

    char copy_str2[1024];
    strcpy_s(copy_str2, str2);

    copy_str2[0] = '&';
    cout << copy_str2 << endl;
    cout << str2 << endl;

    // compare - сравнение
    char s1[1024] = "one ";
    char s2[] = "two";

    cout << "COMPARE " << endl;
    if (strcmp(s1, s2) < 0)
        cout << s1 << " " << s2 << endl;
    else
        cout << s2 << " " << s1 << endl;



    // Конкатенация


    cout << s1 << endl;
    cout << s2 << endl;
    strcat_s(s1, s2);
    cout << "Concatenated: " << s1 << endl;

    // Поиск символа в строке
    char* left_find = strchr(s1, 'o');
    cout << left_find << endl;

    // Поиск символа в строке
    char* right_find = strrchr(s1, 'o');
    cout << right_find << endl;

    // Поиска подстроки в строке
    char s3[]{"Hello world and good morning"};
    char* s4 = strstr(s3, " and ");
    cout << s4 + 5 << endl;
}

void converter() {
    double pi = 3.14;
    int day = 7;
    const char* s1 = "2.731";
    const char* s2 = "12";

    int res1 = atoi(s2);
    double res2 = atof(s1);

    cout << res1 << " " << res2 / 2.0 << endl;

    char res_s[1024];
    _itoa_s(35, res_s, 36);
    cout << res_s << endl;
}

void work_cpp_string() {
    string str1 = "Hello world";
    cout << str1 << endl;

    cout << str1[8] << endl;
    str1[9] = '#';
    cout << str1 << endl;

    // Конвертация к строкам в стиле C
    const char* str2 = str1.data();
    const char* str3 = str1.c_str();

    cout << str1.length() << endl;
    cout << str1.size() << endl;

    string s1 = "one";
    string s2 = "two";

    cout << s1 + " " + s2 << endl;

    string s3 = s2;

    s3[0] = '&';
    cout << s3 << endl;
    cout << s2 << endl;

    string s4 = to_string(3.12);
    cout << s4 << endl;
    cout << stod("4" + s4) << endl;

    cout << s1 << endl;
    cout << s2 << endl;

    // compare - сравнение строк
    if (s1 > s2)
        cout << s1 << " " << s2 << endl;
    else
        cout << s2 << " " << s1 << endl;

    string text[]{ "one", "two", "three" };


}

int main() {
    work_with_string();
    converter();
    //work_cpp_string();
    return 0;
}