#include<iostream>
#include<cstring>

using namespace std;

char *SubStr(const char * str, int pos, int len)
{
    char *new_str = new char[len];
    if (pos >= 0 && pos < strlen(str) && (strlen(str) - len) > 0)
    {
        for (int i = pos, j = 0; i < len; ++i, ++j)
            *(new_str + j) = *(str + i);
    }
    return new_str;
}

int main()
{
    const int STRING_SIZE = 256;
    char text[STRING_SIZE] = "\0";
    char *new_text = NULL;

    cout << "Enter the text. Input complete the point\n";
    cin.getline(text, STRING_SIZE, '.');
    cin.ignore(STRING_SIZE, '\n');

    int new_length;
    cout << "Enter the length for new string: ";
    cin >> new_length;

    int new_pos;
    cout << "Enter the position that start copy to new string: ";
    cin >> new_pos;

    new_text = SubStr(text, new_pos, new_length);

    cout << "Your text:\n";
    cout << "\t" << text << "\n";

    cout << "New text:\n";
    cout << "\t" << new_text << "\n";

    return 0;
}