Csharp Error Handling
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Community Magazine Forums Blogs Channel 9 Documentation APIs and reference Dev c sharp error handling centers Retired content Samples We’re sorry. The content you requested has been removed. You’ll be auto c# error handling in constructor redirected in 1 second. C# C# Programming Guide Exceptions and Exception Handling Exceptions and Exception Handling Exception Handling Exception Handling Exception Handling Using Exceptions Exception Handling
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Creating and Throwing Exceptions Compiler-Generated Exceptions How to: Handle an Exception Using try/catch How to: Execute Cleanup Code Using finally How to: Catch a non-CLS Exception TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This documentation is archived and is
C# Error Handling Framework
not being maintained. Exception Handling (C# Programming Guide) Visual Studio 2015 Other Versions Visual Studio 2013 Visual Studio 2012 Visual Studio 2010 Visual Studio 2008 Visual Studio 2005 A try block is used by C# programmers to partition code that might be affected by an exception. Associated catch blocks are used to handle any resulting exceptions. A finally block contains code that is run regardless of whether or not an exception is thrown in the try block, such as releasing resources that are allocated in the try block. A try block requires one or more associated catch blocks, or a finally block, or both.The following examples show a try-catch statement, a try-finally statement, and a try-catch-finally statement. C# Copy try { // Code to try goes here. } catch (SomeSpecificException ex) { // Code to handle the exception goes here. // Only catch exceptions that you know how to handle. // Never catch base class
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requested has been removed. You’ll be auto redirected in 1 second. C# Keywords Statement Keywords Exception Handling Statements Exception error handling in c# best practices Handling Statements try-catch try-catch try-catch throw try-catch try-finally try-catch-finally TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This https://msdn.microsoft.com/en-us/library/ms173162.aspx documentation is archived and is not being maintained. try-catch (C# Reference) Visual Studio 2015 Other Versions Visual Studio 2013 Visual Studio 2012 Visual Studio 2010 Visual Studio 2008 Visual Studio 2005 Visual Studio .NET 2003 The try-catch statement consists of a try block followed by one or more catch clauses, which specify handlers for different exceptions. RemarksWhen an exception is https://msdn.microsoft.com/en-us/library/0yd65esw.aspx thrown, the common language runtime (CLR) looks for the catch statement that handles this exception. If the currently executing method does not contain such a catch block, the CLR looks at the method that called the current method, and so on up the call stack. If no catch block is found, then the CLR displays an unhandled exception message to the user and stops execution of the program.The try block contains the guarded code that may cause the exception. The block is executed until an exception is thrown or it is completed successfully. For example, the following attempt to cast a null object raises the NullReferenceException exception: C# Copy object o2 = null; try { int i2 = (int)o2; // Error } Although the catch clause can be used without arguments to catch any type of exception, this usage is not recommended. In general, you should only catch those exceptions that you know how to recover from. Therefore, you should always specify an object argument derived from System.Exception For example: C# Copy catch (InvalidCastException e) { } It is poss
Disconnected Data – The DataSet and SqlDataAdapter Lesson 06: Adding Parameters to Commands Lesson 07: Using Stored Procedures C# Tutorial Lesson 1: Getting Started with C# Lesson 2: Operators, Types, and Variables Lesson 3: Control Statements – Selection Lesson http://csharp-station.com/Tutorial/CSharp/Lesson15 4: Control Statements – Loops Lesson 5: Methods Lesson 6: Namespaces Lesson 7: Introduction to Classes Lesson 8: Class Inheritance Lesson 9: Polymorphism Lesson 10: Properties Lesson 11: Indexers Lesson 12: Structs Lesson 13: Interfaces Lesson 14: http://csharp.net-tutorials.com/advanced/exceptions/ Introduction to Delegates and Events Lesson 15: Introduction to Exception Handling Lesson 16: Using Attributes Lesson 17: Enums Lesson 18: Overloading Operators Lesson 19: Encapsulation Lesson 20: Introduction to Generic Collections Lesson 21: Anonymous Methods Lesson 22: error handling Topics on C# Type Lesson 23: Working with Nullable Types LINQ Tutorial Lesson 01: Introduction to LINQ Lesson 02: Forming Projections Articles Links ASP.NET Sites C# Sites .NET Sites Job Sites Object Oriented Sites Other Sites Tools VB.NET Sites Web Services Sites About Contact Link to C# Station Submit a site Support C# Station Terms of Service Lesson 15: Introduction to Exception Handling This lesson teaches how to handle exceptions in your C# programs. c# error handling Our objectives are as follows: Learn what an exception is Implement a routine with a try/catch block Release resources in a finally block Exceptions Exceptions are unforeseen errors that happen in your programs. Most of the time, you can, and should, detect and handle program errors in your code. For example, validating user input, checking for null objects, and verifying the values returned from methods are what you expect, are all examples of good standard error handling that you should be doing all the time. However, there are times when you don't know if an error will occur. For example, you can't predict when you'll receive a file I/O error, run out of system memory, or encounter a database error. These things are generally unlikely, but they could still happen and you want to be able to deal with them when they do occur. This is where exception handling comes in. When exceptions occur, they are said to be "thrown". What is actually thrown is an object that is derived from the System.Exception class. In the next section, I'll be explaining how thrown exceptions are handled with try/catch blocks. The System.Exception class provides several methods and properties for obtaining information on what went wrong. For example, theMessage property provides summary information about what the error was, the Stacktrace property provides informatio
help us prevent some of the most common mistakes. Obviously it can't see every error that might happen, and in those cases, the .NET framework will throw an exception, to tell us that something went wrong. In an earlier chapter, about arrays, I described how we would get an exception if we tried to stuff too many items into an array. Let's bring the example: using System; using System.Collections; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { int[] numbers = new int[2]; numbers[0] = 23; numbers[1] = 32; numbers[2] = 42; foreach(int i in numbers) Console.WriteLine(i); Console.ReadLine(); } } } Okay, try running this example, and you will see what I'm talking about. Do you see what we're doing wrong? We have defined an array of integers with room for 2 items, yet we try to use 3 spaces in it. Obviously, this leads to an error, which you will see if you try to run this example. When run inside Visual C# Express, the IDE gives us some options for the exception, but if you try to execute the program by simply doubleclicking the EXE file, you will get a nasty error. If you know that an error might occur, you should handle it. This is where exceptions are used. Here is a slightly modified version of the code from above: int[] numbers = new int[2]; try { numbers[0] = 23; numbers[1] = 32; numbers[2] = 42; foreach(int i in numbers) Console.WriteLine(i); } catch { Console.WriteLine("Something went wrong!"); } Console.ReadLine(); Let me introduce to you your new best friend when it comes to error handling: the try..catch block. Try running the program now, and see the difference - instead of Visual C# Express/Windows telling us that a serious problem occured, we get to tell our own story. But wouldn't it be nice if we could tell what went wrong? No problem: catch(Exception ex) { Console.WriteLine("An error occured: " + ex.Message); } As you can see, we have added something to the catch statement. We now tell which exception we want caught, in this case the base of all exceptions, the Exception. By doing so, we get some information about the problem which caused the exception, and by outputting the Message property, we get an understandable description of the problem. As I said, Exception is the most general type of exception. The rules of exception handling tells us that we should always use t