When I compile the code using this Ide(https://ide.geeksforgeeks.org/), It shows "Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object" But when I run the code in visual studio, everything is ok. How can I solve these problems? Thanks.
Please post your code; people are reluctant to open links like that. Be sure to show which line has the warning on.
What sort of IDE is it? If it is anything like some of the Java® online interpreters I have seen, it may not compile the code correctly.