C# try catch
Use scenarios for try catch:
1. Generally used in threads, delegates, and is used in threads and delegates because if exceptions occur in threads and delegates, they cannot be caught outside the program, and they need to be handled separately internally.
2. Use the outer layer of the program, such as adding a global exception to capture at the entrance of the program, so that all exceptions occurring in the entire program can be captured.
3. When used in event or principal methods, some small public methods may not be used, except for those that require separate handling of exceptions.
4. In some public methods with more calls, if you use tryc catch, it is best to throw the exception throw and then handle the exception on the upper layer. In this way, when you find the exception, you can know which method is called.
5. Many times when the program is deployed on site, there is no source code to debug. At this time, you need to analyze the log to troubleshoot the problem. Most try catch is used in combination with logNet4. LogNet4 is used to record exception information in catch. The log recorded by lognet4 can record the level of exception method calls and the line number of the specific code to facilitate troubleshooting.
6. Try catch cannot be written too much, nor can it be written too little. Too little writing 1. It is easy to prompt the system's abnormal information pop-up window to the page, but the user cannot understand this prompt information, resulting in a bad user experience. 2. The program is prone to crashing, but it is still impossible to find out why it crashes. Try catch is written too much, and an exception occurs when many methods are called, which may be inconvenient to locate the exception caused by this method called by that function, which is inconvenient to troubleshoot problems.
In C#,try-catch Statements are used for exception handling. It allows you to detect and catch exceptions in code blocks so that you can perform error handling and debugging while the program is running.
try-catch The basic structure of the statement is as follows:
try
{
// Code that may throw exception}
catch (ExceptionType1 ex)
{
// Code for handling specific exception type ExceptionType1}
catch (ExceptionType2 ex)
{
// Code for handling specific exception type ExceptionType2}
catch (ExceptionType3 ex)
{
// Code for handling specific exception type ExceptionType3}
finally
{
// Code that will be executed regardless of whether an exception occurs or not}existtry In the block, you place code that may throw an exception. When executedtry When the code in the block, if an exception occurs, the program will jump to the one that matches the exception type.catch piece. You can add multiple as neededcatch block to handle different types of exceptions. The last onecatch The block usually does not specify an exception type, so it will catch all unhandled exceptions.
finally Blocks are optional and contain codes that will be executed regardless of whether an exception occurs or not. This is useful for cleaning resources or performing necessary actions, such as closing files or database connections.
The following is a usetry-catch Example of statement:
try
{
int result = 0;
result = 10 / 0; // Dividing by zero will raise a DivideByZeroException exception}
catch (DivideByZeroException ex)
{
("The divisor cannot be zero：{0}", );
}
catch (Exception ex)
{
("An unhandled exception occurred：{0}", );
}
finally
{
("The program ends.");
}In the example above, we try to divide 10 by 0, which will raiseDivideByZeroException abnormal.try-catch The statement catches the exception and executes theDivideByZeroException Type matchingcatch piece. Then, regardless of whether an exception occurs, it will be executedfinally Code in the block.
Here are some other usestry-catch Example of statement:
File reading example:
try
{
using (StreamReader reader = new StreamReader(""))
{
string content = ();
(content);
}
}
catch (FileNotFoundException ex)
{
("file not found：{0}", );
}
catch (IOException ex)
{
("File reading error：{0}", );
}
finally
{
("The program ends.");
}Network connection example:
try
{
using (TcpClient client = new TcpClient("", 80))
{
NetworkStream stream = ();
// Carry out network communication operations}
}
catch (SocketException ex)
{
("Network connection abnormality：{0}", );
}
catch (Exception ex)
{
("An unhandled exception occurred：{0}", );
}
finally
{
("The program ends.");
}Database connection example:
try
{
using (SqlConnection connection = new SqlConnection("connectionString"))
{
();
// Perform database operations}
}
catch (SqlException ex)
{
("Database connection exception：{0}", );
}
catch (Exception ex)
{
("An unhandled exception occurred：{0}", );
}
finally
{
("The program ends.");
}4. User input verification:
try
{
// Perform user input verification operations, such as verifying the legality of the user name or password}
catch (FormatException ex)
{
("Input format error：{0}", );
}
catch (InvalidOperationException ex)
{
("Invalid input：{0}", );
}
catch (Exception ex)
{
("An unhandled exception occurred：{0}", );
}
finally
{
("The program ends.");
}These examples show how to use it in different situationstry-catch Statements to handle possible exceptions and perform error handling and program ending operations accordingly.
Do I need to write a try catch in the delegation?
In C#, a delegate is a data type that references methods and can be passed and operated like other objects. When using a delegate, whether the exception needs to be handled using a try-catch statement depends on the specific situation.
If you call the delegate directly in the code, and the method referenced by the delegate may throw an exception, then you need to consider whether you need to use a try-catch statement to catch the exception. For example, if the delegate refers to a method that accesses the database, which may throw an exception when the database connection fails, then when calling the delegate, you may need to use a try-catch statement to catch the exception and handle it accordingly.
On the other hand, if you call multiple methods in your code through delegate chaining, each method needs independent exception handling logic. In this case, you may need to use the try-catch statement in each method to catch the exception and handle it accordingly.
In short, whether you need to use the try-catch statement to handle exceptions in the delegate depends on the specific situation and requirements. If exceptions may exist, it is recommended to use the try-catch statement in the appropriate location to catch and handle exceptions to ensure the stability and reliability of the program.
Write try catch in a c# thread
In C#, it is very important to use a try-catch statement to catch exceptions when writing code in a multithreaded environment. Since multiple threads may execute code at the same time, exceptions may occur in different threads. In order to be able to handle exceptions correctly, it is recommended to use a try-catch statement in the code of each thread.
Here is an example showing how to use a try-catch statement in C# multithreading:
using ;
class Program
{
static void Main(string[] args)
{
// Create two threadsThread thread1 = new Thread(ThreadTask1);
Thread thread2 = new Thread(ThreadTask2);
// Start the thread();
();
// Wait for two threads to complete();
();
}
static void ThreadTask1()
{
try
{
// Execute code here that may throw an exception}
catch (Exception ex)
{
// Handle exceptions("Thread 1abnormal：{0}", );
}
}
static void ThreadTask2()
{
try
{
// Execute code here that may throw an exception}
catch (Exception ex)
{
// Handle exceptions("Thread 2abnormal：{0}", );
}
}
}In the above example, we create two threads, each performing a different task. In the code of each task, we use the try-catch statement to catch possible exceptions and handle them accordingly. This way, no matter which thread has an exception, we can catch and process it to avoid unpredictable behavior of the program.
try catch throw
In programming,try-catch-throw It is a common error handling pattern. These three keywords are usually used together to catch exceptions, handle exceptions, and re-throw exceptions.
throw ： throw Keywords are used to manually throw exceptions in code. When usingthrow When keywords are used, the program will stop the execution of the current method and jump to the most recent one that called the method.catch piece.
It should be noted thatthrow Keywords can only be exported from inheritanceException object of class. In addition, if the method does not provide logic for handling exceptions inside, but throws the exception directly, then it is necessary to use it when calling the methodtry-catch block or declare that the method throws an exception.
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