Visual Studio 2010 C# .NET textbox restrictions

Question

if user entered "!" "?" "," in textbox and press button, this person see ERROR message in label. how can make that? and what is the code?

Answer 1

in the button click handler do:

if (textbox.text.contains("!") || textbox.text.contains("?") || textbox.text.contains(",")){
     //display error message code
     label.text = "ERROR";
}