Using "Find Files" to search a bunch of RTF files for instances of text, I've found that it won't return results if the specified text contains mixed formatting. e.g.:
normal text followed by italics e.g. phrase "testing italics""
normal text followed by bold e.g. phrase "testing bold"
[the same with underlines, or bold underlines etc.].
It will return results if the entire phrase has the same formatting - it's the mix of normal text and text with formatting attributes that seems to be causing the problem.
I've been using DirOpus for searching RTF files for 12 years and only just realised this!
You need an RTF IFilter installed to be able to search RTF correctly, since it is not a plain-text format.
I'd expect MS Office to install one but might be wrong. (I'm surprised one isn't built into Windows, in fact, but maybe it isn't, or it could also be broken.)
IFilters are used by not just Opus but also Windows Search when it indexes file contents, as well as various other software. They convert formats into plain text for searching.
Thanks - I've been looking into this but so far haven't solved the problem. I seem to have an ifilter installed for file type "RTF" and it's set to "index properties and file contents" (in Control Panel->Indexing Options->Advanced->File Types). This is on Win7 64-bit. I'm wondering if this has been screwed up by some fairly recent activity (e.g. an update to my old version of Office, running "Disk Cleanup" or some other software update/install). I've even tried re-registering the 32bit ifilter ("regsvr32 C:\Windows\System32\rtffilt.dll" at an Administrator command prompt). I'll have to dig into this more another time. It certainly searches RTF files OK for text that is all the same format - it's only when there's mixed formatting in the selected phrase that it fails to return a result.
Oh! I forgot to mention, I tried this on a second computer, running latest Windows 10 with DirOpus 12 and had the same problem .... I'll have to do some digging.
Possibly because the text appears as-is within the file. (Which isn't guaranteed with RTF, even without visible formatting differences, but is often the case.)
The contents search that's failing should also fail in File Explorer if the IFilter isn't working.