Don't see how that matters, T.
Recruitment is a funny old business and trying to persuade the folks who have the power to offer the job that you are the best candidate is always going to be hit-and-miss. The reason I say that is because some humans are notoriously bad at making people judgements. To a great extent HR people involved in recruitment are chosen for their ability to make impartial and rationale judgements based on collected evidence. And there are various techniques for doing this and trying to assess exactly what the range of candidates are likely to be able to achieve.
Stop me if you know this (well you can't - so I'm going say it anyway!) but recruitment for all but the most junior jobs is based on a combination of personal skills, attributes or competencies to use the current jargon phrase, plus technical skills. Even the most tecchy recruitment (and I've done a few in my time) needs to show an ability to do more than just 'do the techy business'. I don't know enough to understand the differences between C# and C++, but if I had a technical manager come to me demanding that the pool of candidates must have C# experience, I'd be inclined to ask why. An ability to develop new skills should be part of any employee. Then it boils down to how much I'm going to have to fork out to train the person in C#, plus how long.
Let me ask you a question - what can you do yourself, relatively cheaply, to start learning the basics of C#? - that would really be something to be able to tell at interview.