How to make multiple line text into a single line and add some commas

i want to make a multiple line txt file (reading it on notepad++) into a single line texte with some commas. Example with the text

123
123
123
123

to:

123,123,123,123

Is it possible to do it with notepad++? if not, how can i do it?

>Solution :

Use find/replace. Put yout line terminator in the find and , in the replace and replace all. If you’re on Windows, your line terminator is probably \r\n, but it could be \n or some other value. You will need to set the mode to either extended or regex (regular expression).