Quote:Why can't use string.contains
The reason is in error message, you need to learn to read carefully.
System.NullReferenceException: Object reference not set to an instance of an object.
at WindowsApp1.Form1.Form1_Load(Object sender, EventArgs e) in C:\Users\USER\source\repos\WindowsApp1\WindowsApp1\Form1.vb:line 20
For some reason,
is not a string, and thus, the error.
Lets guess that when
fails, it gives a null pointer instead of a string.
Without doing changes in your code, you can use the debugger to see wgat is going on.
Your code do not behave the way you expect, or you don't understand why !
There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.
Debugger - Wikipedia, the free encyclopedia
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide
Basic Debugging with Visual Studio 2010 - YouTube
Visual Basic / Visual Studio Video Tutorial - Basic Debugging - YouTube
Visual Basic .NET programming for Beginners - Breakpoints and Debugging Tools
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.