Most of Africa is not the sort of place to visit if you need answers to such a question.
I have heard that many big cities in USA are not safe to visit because of armed robberies. I have heard the same about almost every big city in Europe and most in Africa. I have heard that Tiananmen square is not safe to visit if you're a student.
If you're the sort of person who is easily frightened, then you should probably stay away from Africa. It's just like anywhere else: a robbery can occur on the next street, but it doesn't mean that you're next in line. There are many big cities where you'd be advised not to walk out at night and areas to avoid. Africa is the same.