Check out example codes for "c++ replace substrings". It will help you in understanding the concepts better.

Code Example 1

using namespace std;

string ReplaceAllSubstringOccurrences(string sAll, string sStringToRemove, string sStringToInsert)
   int iLength = sStringToRemove.length();
   size_t index = 0;
   while (true)
      /* Locate the substring to replace. */
      index = sAll.find(sStringToRemove, index);
      if (index == std::string::npos)

      /* Make the replacement. */
      sAll.replace(index, iLength, sStringToInsert);

      /* Advance index forward so the next iteration doesn't pick it up as well. */
      index += iLength;
   return sAll;

// EXAMPLE: in usage
string sInitialString = "Replace this, and also this, don't forget this too";
string sFinalString = ReplaceAllSubstringOccurrences(sInitialString, "this", "{new word/phrase}");
cout << "[sInitialString->" << sInitialString << "]\n";
cout << "[sFinalString->" << sFinalString << "]\n";

[sInitialString->Replace this, and also this, don't forget this too]
[sFinalString->Replace {new word/phrase}, and also {new word/phrase}, don't forget {new word/phrase} too] 

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