I want to ask your opinion. I just started to learn C++ and found it very interesting. I am even thinking of getting a diploma in computer science. But I doubt very much that I wil find a job in future, because I am a woman and I am 31. I have read on Internet that job applicants like me (by that time I will be around 34-35 y.o.) don't have big oppotunities. Or if I eventually find a job I will be working with people who are 15 years younger than me and it will be not convenient. So what would you recommend: to give up with this or to continue studying and get a CS diploma? Are there people the same age as me and working in this field?
While at 31 you will generally be seen as a late bloomer, there are people of all ages in the CS industry. When doing my diploma there was a guy there in his sixties!
In our group, I think the youngest developer is about 42 so I wouldn't worry.
Also, keep in mind that programming jobs are in specific industries and it's very helpful to know about those industries. So at your age, you probably know a lot about your current field. Seek a programming job in that field.
Finally, female programmers are still quite rare. The hard truth is that companies will seriously consider you just because you're a woman. I'm not saying that you'll get hired based on your gender alone. I hope that you will be judged solely on your qualifications. But you are must less likely to get rejected out of hand.
I really wouldn't stop learning C++. In my class, almost all of my classmates are either 45 - 60 years old and they all work in the industry. I've also seen quite a few women who are programmers and database designers. In fact, a few of my instructors are women as well... :/
Or if I eventually find a job I will be working with people who are 15 years younger than me and it will be not convenient
Would that be a problem for you? I am in my 50s and working on a BS in computer science I find that I am older than many of my teachers. Any problems I might have had with classmates had nothing to to with them being 20 or 30 years younger than me. Age difference is really only relevant when it comes to social matters, like music preferences or something along that line. The one exception I can think of is when the older person thinks they know more because they are older or the younger just thinks they know everything. That happens in every field though.