When an application encounters an unexpected situation (such as a missing file or input parameter) or a logical error (performing a division-by-zero operation, for example), by default the application will terminate and generate an error display like the one shown in Figure 3.1. Figure 3.1. By default, .NET displays an error message and terminates the application when any error occurs.
Unhandled errors in an application can result in unexpected termination, lost data, and potentially even create security holes if input values are not properly restricted. The Common Language Runtime (CLR) represents all errors as exceptions. An exception is an instance of the Exception class (or a class that inherits from the Exception class). The Framework class library (FCL) includes a large number of standard exception classes that encapsulate information about common errors. Working with instances of these classes allows the developer to provide robust error-handling solutions. The .NET Framework provides two general classes or exceptions that derive from the common Exception class:
Both of these child classes enjoy the same properties and are differentiated only in the source of the exception they represent. Table 3.1 details some of the more common properties of the Exception classes. Table 3.1. Important Members of the Exception Class
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