Position your cursor in first line first character (Strg+home). In Find&Replace activate regex. Activate "backwards". Search for "string" and replace with " string".
Or use the addon "phreplace". With this you don't need " ". Simply use an "enter". -- <https://forum.pspad.com/read.php?2,69974,69976> PSPad freeware editor https://www.pspad.com
