c#programming

Hi, I am a beginner in C# and I am currently learning this program from an online PDF book. Within the book there is a code example and the author stated that it should work if I put it in a C# compiler. However, when I copy and paste the code into an online compiler I got this error message...

I have to wrote a program solving these in an easiest way, not really know how without the mistakes, so thanks for any help. The 'file' contains whats under " John Medeic,MD 10|7|5|3|8|2|1|0|9|3|4|5|5|6|7|2|3 " Task. 1. Load and correctly interpret the data contained in the file. As a result...

I have a form with a group box that contains 3 radio buttons. When I run the form none of them are selected. I want the first radio button to always be selected when the form is run, but I'm not sure which property to change for that. I tried setting the Checked property to True but that didn't...