Question

I have this string :

Hello my name is Marco

and I’d like to replace the first space (between Hello and my) with <br />. Only the first.

What’s the best way to do it on C#/.NET 3.5?

Answer 1

No need to add substrings, following will find the first space instance only.
From MSDN:

Reports the zero-based index of the first occurrence of the specified
string in this instance.

  string x = "Hello my name is Marco";
  int index = x.IndexOf(" ");
  if (index >= 0)
  {
      x=x.Remove(index,1);
      x = x.Insert(index, @"<br />");
  }

Edit: If you are not sure if space will occur, some validations must come into place. I have edit the answer accordingly.