Simple coding to Stack

int main()
{

  string sentence;
  int length;


  cout << "Enter the sentence now." << endl;
    getline(cin, sentence);


  for(int i = 0; i < sentence[i]; i++)
  {



    if(sentence[i]==';')
    cout<<" ";
    else if(sentence[i] != ' ')
    {
        cout << sentence[i];
    }
    else if(sentence[i] == ' ')
    {
        cout << endl;
    }

  }
}

I need help in this code to change into stack coding method. At least you can show me some clue how to change this code into simple stack code.