Throw in C #

Throw throws/passes an exception by using the throw statement in the Catch Block. exceptions that can be changed. For example, we can throw a new exception. Throw statements have various types and are necessary.

Example
First, let's take a look at the three methods called A, B, and C. They use different throw statements. Method A uses a throw statement without parameters. This can be seen as a rethrow (continue to throw)-It will throw the same exception that has already occurred

Continue. Method B throw is a named exception variable. This is not a complete rethrow-because it throws the same exception. But stacktrace is changed. If necessary, we can collect some exception information, and method C creates a new exception.
Tip: You can use this method to handle custom errors.
Example of using the throw statement

 Using  System;  Class  Program {  Static   Void  Main (){  Try  {A (); B (); C ( Null  );}  Catch  (Exception ex) {console. writeline (Ex );}}  Static   Void  A (){  //  Rethrow syntax.      Try  {  Int Value = 1 / Int . Parse ( " 0  "  );}  Catch  {  Throw  ;}}  Static   Void  B (){  //  Filter exception types.      Try  {  Int Value = 1 /Int . Parse ( "  0  "  );}  Catch  (Dividebyzeroexception ex ){  Throw  Ex ;}}  Static   Void C ( String  Value ){  //  Create a new exception.      If (Value = Null  ){  Throw   New Argumentnullexception ( "  Value  "  );}}} 

 

ProgramPossible output results

 
System. dividebyzeroexception: attempted to divide by zero. system. dividebyzeroexception: attempted to divide by zero. system. argumentnullexception: value cannot beNull. Parameter Name: Value
 

 

Rethrow

Next, let's look at more details about rethrows. The rethrow must be a throw statement without parameters. If throw ex is used, targetsie (targetsite obtains the method for throwing this exception from the stack trace. If the stack trace is empty, targetsite also returns an empty reference. -Note by the translator) and stacktrace are both changed.

In the following program, the X () method uses the rethrow statement. Y () uses the throw ex statement. Let's take a look at the method that causes an exception when the rethrow statement is used, that is, the abnormal targetsite is within stringtonumber --- an int. parse method.

However, when Throw ex is used. Like in Y (), the abnormal targetsite is modified to the current y () method.
Example of testing rethrow

 Using  System;  Class  Program {  Static   Void  Main (){  Try  {X ();} Catch  (Exception ex) {console. writeline (ex. targetsite );}  Try  {Y ();}  Catch  (Exception ex) {console. writeline (ex. targetsite );}}  Static   Void  X (){  Try  {  Int . Parse ( "  ? "  );}  Catch  (Exception ){  Throw ; //  [Rethrow construction]  }}  Static   Void  Y (){  Try  {  Int . Parse ( "  ? "  );}  Catch  (Exception ex ){  Throw Ex; //  [Throw captured ex variable]  }}} 

 

Output

 
Void stringtonumber (system. String,...) void y ()
 

 

Summary:
The exception handling mechanism provides an optional control path that separates the exception logic from the exception handling. In addition, throw can be used to rethrow an exception or generate a new exception.
Translation: http://www.dotnetperls.com/throw

This article by bystander translation, reprint please note http://leaver.me