main.cpp

#include <bits/stdc++.h>

using namespace std;

void string_manipulation_iterator (string &s, const string &oldVal, const string &newVal)
{
  for (auto iter {s.begin()}; iter < s.end(); ++iter)
    {
      if (*iter == oldVal.front())
        {
          for (int i {1}; i != oldVal.size(); ++i)
            {
              if (*(iter + i) != oldVal.at (i))
                {
                  break;
                }
              if (i + 1 == oldVal.size())
                {
                  auto pos = distance (s.begin(), iter);
                  s.erase (pos, oldVal.size());
                  s.insert (pos, newVal);
                  iter = s.begin() + pos + int (newVal.size());
                }
            }
        }
    }
}

void string_manipulation_index_and_replace (string &s, const string &oldVal, const string &newVal)
{
  for (int i {0}; i < s.size(); ++i)
    {
      if (s.at (i) == oldVal.at (0))
        {
          for (int j {1}; j != oldVal.size(); ++j)
            {
              if (s.at (i + j) != oldVal.at (j))
                {
                  break;
                }
              if (j + 1 == oldVal.size())
                {
                  s.replace (i, oldVal.size(), newVal);
                }
            }
        }
    }
}

string &prefix_and_suffix (string &name, const string &prefix, const string &suffix)
{
  name.insert (0, prefix);
  //    name.append(suffix);
  name.insert (distance (name.begin(), name.end()), suffix);
  return name;
}

int main (int argc, char *argv[])
try
  {
    string s {"there was tho tho and thru"};

    cout << s << endl;
    string_manipulation_iterator (s, "tho", "though");
    cout << s << endl;
    string_manipulation_iterator (s, "thru", "through");
    cout << s << endl;

    cout << "---------------------" << endl;

    s = "there was tho tho and thru";

    cout << s << endl;
    string_manipulation_index_and_replace (s, "tho", "though");
    cout << s << endl;
    string_manipulation_index_and_replace (s, "thru", "through");
    cout << s << endl;

    cout << "---------------------" << endl;

    string s1 = "Anna";
    cout << prefix_and_suffix (s1, "Ms. ", ", The III Queen of Mars.");

    return 0;
  }
catch (exception &e)
  {
    cerr << "Error: " << e.what() << endl;
  }