Question

Is there a C++ version of ungetc?

That is, can I put a character back onto an istream?

Answer 1

Yes. istream::putback is the same as ungetc except if using unget():

You can’t lie with unget(). It “ungets” the last-read character. You
can lie with putback(c). You can “putback” some character other than
the last-read character. Sometimes putting back a character other than
the last-read character can be useful.

Also, if the underlying read buffer really does have buffering
capability, you can “putback” more than one character. I think
ungetc() is limited to one character.