winforms - How to bold a part of string being passed into TextBox in c# -

i have string builder value appending @ runtime via placeholder. once string builder has appended, assigned text box (not rich txt) show in ui.

i want part of text bold.

sb.appendformat("added {0} {1}:\n{2}", datetime.tostring(), username, note); txt.text = sb.tostring();

expected output:

added 9/01/2016 8:47:19 pm vinoth: testing purpose

how can achieve this? there anyway of looping on words : symbol until want bold?

you have build text in sections.

either different textboxes/textblocks or single richtextbox separate runs sections want in different style.

SoEM