try-catch

问题 In an answer to a previous question: How can I use 'do I have root access?' as a conditional in bash? The suggestion to 'try to do something and detect if it fails' instead of 'check permission and then do something' I have found plenty of rationale for this e.g.: Thorough use of 'if' statements or 'try/catch' blocks? What is the advantage of using try {} catch {} versus if {} else {} However, I have found very little clear information about how to implementing try/catch in bash. I would

问题 Is there a way to handle errors in SYBASE , such as the TRY-CATCH block you can use in MS SQL Server , Oracle , etc? I've searched the web and the only option I found was the global variable @@error , but it didn' work as I expected, for example, the following code: begin tran update table1 set name = 'new name' where name = 'old name' update table2 set id = 1 where id = 30 -- suppose id has a unique constraint and there's already a row with id = 1 IF @@error = 0 begin print 'commited' commit

问题 I use JSLint all the time, but just today, I came across an error that I've never seen before. With the following code, I got the error shown below: try { document.execCommand('BackgroundImageCache', false, true); } catch (ex) {} Error: Expected 'ignore' and instead saw 'ex'. } catch (ex) {} So I changed my code to the following, and the error went away: try { document.execCommand('BackgroundImageCache', false, true); } catch (ignore) {} I can't find any explanation on the Internet regarding

问题 I use JSLint all the time, but just today, I came across an error that I've never seen before. With the following code, I got the error shown below: try { document.execCommand('BackgroundImageCache', false, true); } catch (ex) {} Error: Expected 'ignore' and instead saw 'ex'. } catch (ex) {} So I changed my code to the following, and the error went away: try { document.execCommand('BackgroundImageCache', false, true); } catch (ignore) {} I can't find any explanation on the Internet regarding

问题 This is a follow up to the question Nested stored procedures containing TRY CATCH ROLLBACK pattern? In the catch block I use a stored procedure to report (reraise) the error by reading from ERROR_MESSAGE(), ERROR_PROCEDURE(), ERROR_LINE(), etc. As described here I also have a check so that it can determine if the error has already been rethrown (this happens with nested stored procedures as the error information is passed down through each TRY CATCH block). What I would like to do, either

问题 I've created a bunch of functions and I need very similar except clauses in all of them, but I hate having so many lines of try and except clauses and the same code inside of each function. For example: import sys import random def foo(): num=random.random() try: if num>0.5: print 'OK' elif num>0.25: raise NameError('Too Small') else: raise KeyboardInterrupt except NameError: print "%s had a NameError" % sys._getframe().f_code.co_name except: print "%s had a different Error" % sys._getframe()

问题 Does try catch outside of: await Task.Run(() => make sense or just use them only inside of await? private async void Test() { try { await Task.Run(() => { try { DoingSomething(); } catch (Exception ex) { log.Error(ex.Message); } }); } catch (Exception ex) { log.Error(ex.Message); } } 回答1: If you handle Exception inside the delegate (in your case just for logging purpose), await will not raise an exception in normal circumstances. This should be fine. private async Task Test() { await Task.Run

问题 The following catch() is not called: void test(void) { int i=1,j=0,k; try { k = i/j; } catch(...) { ...handle it... } } Is there a way to catch this kind of exception? 回答1: Please check http://linux.die.net/man/1/gcc there is a compiler option -mcheck-zero-division to handle this. Alternatively, installing a SIGFPE handler might be an option, A float div by 0 would then generate a 'FPE_ZERODIVIDE' signal(SIGFPE, (fptr) FPE_ExceptionHandler); void FPE_ExceptionHandler(int nSig,int nErrType,int

问题 My senior colleague tells me to wrap every method within a try-catch block so they can trace where exceptions occurs to help debug issues quicker. Is it better to wrap every method in a Try Catch such as this to: Public int foo() { try { //do something }catch(Exeception ex) { //do something with ex } } Or is it better to catch exceptions where I think they may occur? E.g. doing something with an array may cause the IndexOutOfRangeException will occur. //wrap this in try catch int[] array =

问题 try { $matrix = Query::take("SELECT moo"); //this makes 0 sense while($row = mysqli_fetch_array($matrix, MYSQL_BOTH)) //and thus this line should be an error { } return 'something'; } catch(Exception $e) { return 'nothing'; } However instead of just going to catch part and returning nothing it shows a warning Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in the line starting with while . I have never came up to using exceptions in php, but used them a lot