BT11.cpp

#include <string>
#include <iostream>
#include <cmath>
#include <map>

void q1(void)
{
    std::string str;
    std::cout << "Input: ";
    std::cin >> str;

    std::cout << str[0] << str[floor(str.length() / 2)] << str[str.length() - 1] << std::endl;
}

void q2(void)
{
    std::string str1;
    std::cout << "s1: ";
    std::cin >> str1;

    std::string str2;
    std::cout << "s2: ";
    std::cin >> str2;

    int mid = floor(str1.length() / 2);

    std::string str3 = str1.substr(0, mid) + str2 + str1.substr(mid, str1.length() - 1);

    std::cout << str3 << std::endl;
}

void q3(void)
{
    std::string str;
    std::cout << "Input: ";
    std::cin >> str;

    std::string lowerStr;
    std::string upperStr;

    for (int i = 0; i < str.length(); i++)
    {
        if (std::islower(str[i]))
        {
            lowerStr += str[i];
        }
        else
        {
            upperStr += str[i];
        }
    }

    std::cout << lowerStr << upperStr << std::endl;
}

void q4(void)
{
    int chars, digits, symbols;
    chars = digits = symbols = 0;
    std::string str;
    std::cout << "Input: ";
    std::cin >> str;

    for (int i = 0; i < str.length(); i++)
    {
        if (std::isdigit(str[i]))
        {
            digits++;
        }
        else if (std::isalpha(str[i]))
        {
            chars++;
        }
        else
        {
            symbols++;
        }
    }

    std::cout << "Chars: " << chars << std::endl
              << "Digits: " << std::endl
              << digits << "Symbols: " << symbols << std::endl;
}

void q5(void)
{
    std::string str;
    std::cout << "Input: ";
    std::getline(std::cin, str);

    std::string sub = "hk";

    std::transform(str.begin(), str.end(), str.begin(), ::tolower);

    std::size_t pos = str.find(sub, 0);
    int count = 0;
    while (pos != std::string::npos)
    {
        count++;
        pos = str.find(sub, pos + 1);
    }

    std::cout << "The HK count is: " << count << std::endl;
}

void q6(void)
{
    std::string str;
    std::cout << "Input: ";
    std::getline(std::cin, str);

    std::map<char, int> chars;

    for (int i = 0; i < str.length(); i++)
    {
        chars[str[i]]++;
    }

    std::cout << "{ ";
    std::for_each(chars.begin(), chars.end(),
                  [](const std::pair<char, int> &p)
                  {
                      std::cout << p.first << ": " << p.second << ", ";
                  });
    std::cout << "}" << std::endl;
}

void q7(void)
{
    std::string str;
    std::cout << "Input: ";
    std::getline(std::cin, str);

    std::string sub = "Emma";

    std::size_t pos = str.rfind(sub);

    if (pos != std::string::npos)
    {
        std::cout << "Last occurrence of Emma starts at index " << pos << std::endl;
    }
    else
    {
        std::cout << "No occurrences of Emma were found." << std::endl;
    }
}

void q8(void)
{
    std::string str;
    std::cout << "Input: ";
    std::getline(std::cin, str);

    std::string strout;

    for (int i = 0; i < str.length(); i++)
    {
        if (std::isdigit(str[i]))
        {
            strout += str[i];
        }
    }

    std::cout << strout << std::endl;
}

void q9(void)
{
    std::string str;
    std::cout << "Input: ";
    std::getline(std::cin, str);
    for (int i = 0; i < str.length(); i++)
    {
        if (!std::isdigit(str[i]) && !std::isalpha(str[i]) && !(str[i] == ' '))
        {
            str[i] = '#';
        }
    }

    std::cout << str << std::endl;
}

int main(void)
{
    q1();
    q2();
    q3();
    q4();
    q5();
    q6();
    q7();
    q8();
    q9();
    return 0;
}