Roman

#include<iostream>
#include<fstream>
#include<limits>
#include<vector>
#include<iterator>
#include<algorithm>
#include<string>
using namespace std;

int main()
{
  const string filein = "D:\\numbers_in.txt";
  const string fileout = "D:\\numbers_out.txt";
  vector<double> v;

  ios_base::sync_with_stdio(false);

  if(ifstream ifs(filein); ifs)
  {
    transform(istream_iterator<string>{ifs}, {}, back_inserter(v), [](const auto& xs){
      double d = numeric_limits<double>::infinity();
      try
      {
        d = stod(xs);
      }
      catch(...)
      {
        cout << "wrong\n";
      }
      return d;
    });
  }

  copy(v.begin(), v.end(), ostream_iterator<double>{cout, " "});

  if(ofstream ofs(fileout); ofs)
  {
    copy(v.begin(), v.end(), ostream_iterator<double>{ofs, " "});
  }

  cin.get();
}

#include<iostream>
#include<fstream>
#include<limits>
#include<vector>
#include<iterator>
#include<algorithm>
#include<string>
#include<sstream>
using namespace std;

auto parse_line = [](istream& is)
{
  vector<double> row;
  transform(istream_iterator<string>{is}, {}, back_inserter(row), [](const auto& xs){
      double d = numeric_limits<double>::infinity();
      try
      {
        d = stod(xs);
      }
      catch(...)
      {
        cout << "wrong\n";
      }
      return d;
    });
  return row;
};

int main()
{
  const string filein = "D:\\numbers_in.txt";
  const string fileout = "D:\\numbers_out.txt";

  vector<vector<double>> matrix;

  ios_base::sync_with_stdio(false);

  if(ifstream ifs(filein); ifs)
  {
    string line;
    while(getline(ifs, line))
    {
      istringstream is{ line };
      matrix.push_back(parse_line(is));
    }
  }

  for(const auto& v : matrix)
  {
    copy(v.begin(), v.end(), ostream_iterator<double>{cout, " "});
    cout << "\n";
  }
  
  if(ofstream ofs(fileout); ofs)
  {
    for(const auto& v : matrix)
    {
      copy(v.begin(), v.end(), ostream_iterator<double>{ofs, " "});
      ofs << "\n";
    }
  }

  cin.get();
}

using Matrix = vector<vector<double>>;

auto find_min = [](const Matrix& m)
{
  vector<double> values;
  for(const auto& row : m)
  {
    values.push_back(*min_element(row.begin(), row.end()));
  }
  return *min_element(values.begin(), values.end());
};

// ... 

cout << "Min element: " << find_min(matrix) << endl;

#include <iostream> 
using namespace std;
int main()
{
  float x, y;
  char z;
  char c = 'n';
  do {
    cout << "Write your first number:";
    cin >> x;
    cout << "Write your second number:";
    cin >> y;
    cout << "Write your sign:";
    cin >> z;
    switch(z)
    {
      case '+':
      {
        cout << "Your answer: "
             << x << "+" << y << "="
             << x + y
             << "\n";
      }
      break;

      case '-':
      {
        cout << "Your answer: "
             << x << "-" << y << "="
             << x - y
             << "\n";
      }
      break;

      case '*':
      {
        cout << "Your answer: "
             << x << "*" << y << "="
             << x * y
             << "\n";
      }
      break;

      case '/':
      {
        if(y == 0)
        {
          cout << "You cant division!" << endl;
        }
        else
        {
          cout << "Your answer: "
               << x << "/" << y << "="
               << x / y
               << "\n";
        }
      }  
      break;
    }
    cout << "continue? (y/n): ";
  } while((cin >> c) && c == 'y');
}

#include<iostream>
#include<string>
#include<sstream>
using namespace std;

struct Entry
{
  string name;
  int age;
};

istream& operator>>(istream& is, Entry& e)
{
  is >> e.name >> e.age;
  return is;
}

ostream& operator<<(ostream& os, Entry& e)
{
  os << e.name << " " << e.age;
  return os;
}

int main()
{  
  string line;

  getline(cin, line);
  istringstream is(line);

  is.exceptions(ios_base::failbit);

  Entry e;
  try // I know it was wrong.
  {
    while(is >> e)
    {
      cout << e << "\n";
    }
  }
  catch(exception& e)
  {
    cerr << e.what() << endl;
  }

  cout << "Done!\n";

  string answer;
  cin >> answer;

  system("pause");
}

#include<iostream>
#include<sstream>
#include<string>
#include<fstream>

using namespace std;

string process(const string& filename)
{
  ostringstream os;
  if(ifstream ifs(filename); ifs)
  {
    string line;
    while(getline(ifs, line))
    {
      if(auto pos = line.find("link"); pos != string::npos)
      {
        pos = line.find('\"', pos);
        auto end = line.find('\"', pos + 1);
        os << process(line.substr(pos + 1, end - pos - 1));
        continue;
      }
      os << line << "\n";
    }
  }
  return os.str();
}

int main()
{
  cout << process("text.txt");
  cin.get();
}

#include <iostream>
#include <set>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{
  set<int> nums;
  generate_n(inserter(nums, nums.end()), 42, []{ return rand() % 42; });
  int n = 0; cin >> n;
  cout << "\n" 
       << ((nums.find(n) != nums.end()) ? "" : "Not ") 
       << "Found" 
       << endl;
}

#include <iostream>

bool find(int a[], int sz, int value)
{
  if(sz == -1)
    return false;
  else if(a[sz] == value)
    return true;
  else
    return find(a, sz - 1, value);
}

int main()
{
  int nums[] = { 4, 6, 9, 11 };

  int i = 0;

  std::cin >> i;

  std::cout << "\n" 
            << std::boolalpha 
            << find(nums, sizeof(nums) / sizeof(int) - 1, i);
}

#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main(int argc, char* argv[])
{
  if(argc > 0)
  {
    vector<string> args(&argv[1], &argv[argc]);
    for(const auto& n : args)
    {
      cout << "Hello " << n << "\n";
    }
  }
}

//...
for(int i = 1; i < argc; ++i)
{
  cout << "Hello " << argv[i] << "\n";
}
//...

13. (*3) Напишите функцию обработки ошибок, первый параметр который подобен форматирующей
строке-параметру printf() и содержит форматы %s, %c и %d. За ним может следовать произвольное
количество числовых параметров. Функцию printf() не используйте. Если смысл формата %s и
других форматов вам неизвестен, обратитесь к $$10.6. Используйте stdarg.h.

#include <iostream>

template<typename... Arg>
auto say_hello(std::ostream& os, Arg... args)
{
  ((os << args << "\n") , ...);
}

int main(int argc, char* argv[])
{
  say_hello(std::cout, "Name", "Name1", "Name2");
  std::cin.get();
}

#include<iostream>
#include<string>

using namespace std;

using mytype = pair<string, int>;

istream& operator>>(istream& is, mytype& m)
{
  while(isalpha(is.peek()))
  {
    m.first.push_back(is.get());
  }
  is >> m.second;
  return is;
}

ostream& operator<<(ostream& os, const mytype& m)
{
  return os << m.first << m.second;
}


int main()
{
  mytype mt;

  cin >> mt;

  cout << mt << endl;
}