Have you used any of the C++ interpreters (not compilers)?

cint is the command processor for the particle physics analysis package ROOT. I use it regularly, and it works very well for me.

It is fairly complete and gets on well with compiled code (you can load compiled modules for use in the interpreter...)

late edit:: Copied from a later duplicate because the poster on that questions didn't seem to want to post here: igcc. Never tried it personally, but the web page looks promising.

I have (about a year ago) played around with Ch and found it to be pretty good.

Long ago, I used a C++ interpreter called CodeCenter. It was pretty nice, although it couldn't handle things like bitfields or fancy pointer mangling. The two cool things about it were that you could watch when variables changed, and that you could evaluate C/C++ code on the fly while debugging. These days, I think a debugger like GDB is basically just as good.

Also long ago I used a product call Instant C but I don't know that it ever developed further

I looked at using ch a while back to see if I could use it for black box testing DLLs for which I am responsible. Unfortunately, I couldn't quite figure out how to get it to load and execute functions from DLLs. Then again, I wasn't that motivated and there may well be a way.