C++ string Replacing a word in text by asterisks.

#include <iostream>
#include <string>
#include <cctype>

using std::string;

int main()//from www  .j  a  v  a 2 s .co  m
{
  string text;
  string word;
  char asterisk  = '*';
  std::cout << "Enter some text terminated by *:\n";
  std::getline(std::cin, text, '*');
  std::cout << "\nEnter the word to be replaced: ";
  std::cin >> word;
  string uc_word {word};

  for (auto& ch : uc_word)
    ch = std::toupper(ch);

  const string separators {" ,;:.\"!?'\n"};                  // Word  delimiters

  int start {text.find_first_not_of(separators)};
  int end {};
  bool is_word {false};

  while (start != string::npos)
  {
    end = text.find_first_of(separators, start + 1);
    if (end == string::npos)
      end = text.length();

    // Compare the word found in uppercase with uc_word
    if (end - start == word.length())
    {
      is_word = true;                                     
      for (int i {start}; i < end; ++i)                   
        if (uc_word[i - start] != toupper(text[i]))       
        {
          is_word = false;                                
          break;      
        }
      if (is_word)                                        
        for (int i {start}; i < end; ++i)                 
          text[i] = asterisk;
    }
    start = text.find_first_not_of(separators, end + 1);
  }

  std::cout << std::endl << text << std::endl;
}