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  • Why do Pascal control structures appear to be inconsistent?

    - by 70Mike
    Most Pascal control structures make sense to me, like: for ... do {statement}; if (condition) then {statement}; while (condition) do {statement}; where the {statement} is either a single statement, or a begin ... end block. I have a problem with: repeat {statement-list} until (expression); try {statement-list} except {statement-list} end; Wouldn't it be better that repeat and try have the same general structure, accepting only a single statement or a begin ... end block, instead of having a statement-list that's not formally blocked with a begin and an end?

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  • Should java try blocks be scoped as tightly as possible?

    - by isme
    I've been told that there is some overhead in using the Java try-catch mechanism. So, while it is necessary to put methods that throw checked exception within a try block to handle the possible exception, it is good practice performance-wise to limit the size of the try block to contain only those operations that could throw exceptions. I'm not so sure that this is a sensible conclusion. Consider the two implementations below of a function that processes a specified text file. Even if it is true that the first one incurs some unnecessary overhead, I find it much easier to follow. It is less clear where exactly the exceptions come from just from looking at statements, but the comments clearly show which statements are responsible. The second one is much longer and complicated than the first. In particular, the nice line-reading idiom of the first has to be mangled to fit the readLine call into a try block. What is the best practice for handling exceptions in a funcion where multiple exceptions could be thrown in its definition? This one contains all the processing code within the try block: void processFile(File f) { try { // construction of FileReader can throw FileNotFoundException BufferedReader in = new BufferedReader(new FileReader(f)); // call of readLine can throw IOException String line; while ((line = in.readLine()) != null) { process(line); } } catch (FileNotFoundException ex) { handle(ex); } catch (IOException ex) { handle(ex); } } This one contains only the methods that throw exceptions within try blocks: void processFile(File f) { FileReader reader; try { reader = new FileReader(f); } catch (FileNotFoundException ex) { handle(ex); return; } BufferedReader in = new BufferedReader(reader); String line; while (true) { try { line = in.readLine(); } catch (IOException ex) { handle(ex); break; } if (line == null) { break; } process(line); } }

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  • What does "[IN-USE] account is locked by another session or for maintenance, try again." mean?

    - by John
    I'm in the process of migrating a computer from Windows To Ubuntu. I followed these instructions to move my Thunderbird emails over. The emails that I moved show up, but when I try to check for new emails I get this message: Sending of password did not succeed. Mail server pop.windstream.net responded: [IN-USE] account is locked by another session or for maintenance, try again. I click OK and another box pops up saying: Login to server pop.windstream.net failed. With 3 options: "Enter new password" (I'm SURE the one I'm typing is correct) "Cancel" "Retry" I've tried all 3. Retyping my password, clicking "Retry", same result. While I was typing this, I got a toast that said: Thunderbird's attempt to connect to pop.windstream.net has timed out. What is causing this and how can I fix it?

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  • Subterranean IL: Compiling C# exception handlers

    - by Simon Cooper
    An exception handler in C# combines the IL catch and finally exception handling clauses into a single try statement: try { Console.WriteLine("Try block") // ... } catch (IOException) { Console.WriteLine("IOException catch") // ... } catch (Exception e) { Console.WriteLine("Exception catch") // ... } finally { Console.WriteLine("Finally block") // ... } How does this get compiled into IL? Initial implementation If you remember from my earlier post, finally clauses must be specified with their own .try clause. So, for the initial implementation, we take the try/catch/finally, and simply split it up into two .try clauses (I have to use label syntax for this): StartTry: ldstr "Try block" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndTry: StartIOECatch: ldstr "IOException catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndIOECatch: StartECatch: ldstr "Exception catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End EndECatch: StartFinally: ldstr "Finally block" call void [mscorlib]System.Console::WriteLine(string) // ... endfinally EndFinally: End: // ... .try StartTry to EndTry catch [mscorlib]System.IO.IOException handler StartIOECatch to EndIOECatch catch [mscorlib]System.Exception handler StartECatch to EndECatch .try StartTry to EndTry finally handler StartFinally to EndFinally However, the resulting program isn't verifiable, and doesn't run: [IL]: Error: Shared try has finally or fault handler. Nested try blocks What's with the verification error? Well, it's a condition of IL verification that all exception handling regions (try, catch, filter, finally, fault) of a single .try clause have to be completely contained within any outer exception region, and they can't overlap with any other exception handling clause. In other words, IL exception handling clauses must to be representable in the scoped syntax, and in this example, we're overlapping catch and finally clauses. Not only is this example not verifiable, it isn't semantically correct. The finally handler is specified round the .try. What happens if you were able to run this code, and an exception was thrown? Program execution enters top of try block, and exception is thrown within it CLR searches for an exception handler, finds catch Because control flow is leaving .try, finally block is run The catch block is run leave.s End inside the catch handler branches to End label. We're actually running the finally before the catch! What we do about it What we actually need to do is put the catch clauses inside the finally clause, as this will ensure the finally gets executed at the correct time (this time using scoped syntax): .try { .try { ldstr "Try block" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } catch [mscorlib]System.IO.IOException { ldstr "IOException catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } catch [mscorlib]System.Exception { ldstr "Exception catch" call void [mscorlib]System.Console::WriteLine(string) // ... leave.s End } } finally { ldstr "Finally block" call void [mscorlib]System.Console::WriteLine(string) // ... endfinally } End: ret Returning from methods There is a further semantic mismatch that the C# compiler has to deal with; in C#, you are allowed to return from within an exception handling block: public int HandleMethod() { try { // ... return 0; } catch (Exception) { // ... return -1; } } However, you can't ret inside an exception handling block in IL. So the C# compiler does a leave.s to a ret outside the exception handling area, loading/storing any return value to a local variable along the way (as leave.s clears the stack): .method public instance int32 HandleMethod() { .locals init ( int32 retVal ) .try { // ... ldc.i4.0 stloc.0 leave.s End } catch [mscorlib]System.Exception { // ... ldc.i4.m1 stloc.0 leave.s End } End: ldloc.0 ret } Conclusion As you can see, the C# compiler has quite a few hoops to jump through to translate C# code into semantically-correct IL, and hides the numerous conditions on IL exception handling blocks from the C# programmer. Next up: catch-all blocks, and how the runtime deals with non-Exception exceptions.

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  • Ubuntu is not booting - "No init fount. Try passing init= bootarg." , Install from Windows (Wubi)

    - by Hunzai
    Unbuntu 10.04 installed from Windows 7 (Wubi filesystme), Now Ubuntu is not booting giving this error. Target filesystem doesn't have /sbin/init. No init fount. Try passing init= bootarg. BusyBox v1.13.3 (Ubuntu 1:1.13.3-1ubuntu7) built in shell (ash) Enter 'help' for a list of build in commands (initramfs) The solutions given by folk is like [http://learntoconfigure.wordpress.com/2012/11/29/ubuntu-cannot-boot-no-init-found-try-passing-initbootarg/] Can't solved my problem because Ubuntu is installed from windows and all the drive shows of windows, Can anyone help me? thanks, Hunzai

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  • Should I try to write simple key-value storage by myself?

    - by shabunc
    I need a key-value storage in a simplest form we can think of. Keys should be some fixed-length strings, values should be some texts. This key-value storage should have an HTTP-backed API. That's basically it. As you can see, there is no big difference between such storage and some web application with some upload functionality. The thing is - it'll take few hours (including tests and coffee drinking) to write something like this. "Something like this" will be fully under my control and can be tuned on demand. Should I, in this specific case, not try to reinvent bicycles? Is it better to use some of existing NoSQL solutions. If yes, which one exactly? If, say, I'd needed something SQL-like, I won't ask and won't try to write something by myself. But with NoSQL I just don't know what is adequate and what is not.

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  • iPhone: Repeating Rows in Each Section of Grouped UITableview

    - by Rank Beginner
    I'm trying to learn how to use the UITableView in conjunction with a SQLite back end. My issue is that I've gotten the table to populate with the records from the database, however I'm having a problem with the section titles. I am not able to figure out the proper set up for this, and I'm repeating all tasks under each section. The table looks like this. The groups field is where I'm trying to pull the section title from. TaskID groups TaskName sched lastCompleted nextCompleted success 1 Household laundry 3 03/19/2010 03/22/2010 y 1 Automotive Change oil 3 03/20/2010 03/23/2010 y In my viewDidLoad Method, I create an array from each column in the table like below. //Create and initialize arrays from table columns //______________________________________________________________________________________ ids =[[NSMutableArray alloc] init]; tasks =[[NSMutableArray alloc] init]; sched =[[NSMutableArray alloc] init]; lastComplete =[[NSMutableArray alloc] init]; nextComplete =[[NSMutableArray alloc] init]; weight =[[NSMutableArray alloc] init]; success =[[NSMutableArray alloc] init]; group =[[NSMutableArray alloc] init]; // Bind them to the data //______________________________________________________________________________________ NSString *query = [NSString stringWithFormat:@"SELECT * FROM Tasks ORDER BY nextComplete "]; sqlite3_stmt *statement; if (sqlite3_prepare_v2( database, [query UTF8String], -1, &statement, nil) == SQLITE_OK) { while (sqlite3_step(statement) == SQLITE_ROW) { [ids addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 0)]]; [group addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 1)]]; [tasks addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 2)]]; [sched addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 3)]]; [lastComplete addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 4)]]; [nextComplete addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 5)]]; [success addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 6)]]; [weight addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 7)]]; } sqlite3_finalize(statement); } In the table method:cellForRowAtIndexPath, I create controls on the fly and set their text properties to objects in the array. Below is a sample, I can provide more but am already working on a book here... :) /create the task label NSString *tmpMessage; tmpMessage = [NSString stringWithFormat:@"%@ every %@ days, for %@ points",[tasks objectAtIndex:indexPath.row],[sched objectAtIndex:indexPath.row],[weight objectAtIndex:indexPath.row]]; CGRect schedLabelRect = CGRectMake(0, 0, 250, 15); UILabel *lblSched = [[UILabel alloc] initWithFrame:schedLabelRect]; lblSched.textAlignment = UITextAlignmentLeft; lblSched.text = tmpMessage; lblSched.font = [UIFont boldSystemFontOfSize:10]; [cell.contentView addSubview: lblSched]; [lblSched release]; My numberOfSectionsInTableView method looks like this // Figure out how many sections there are by a distinct count of the groups field // The groups are entered by user when creating tasks //______________________________________________________________________________________ NSString *groupquery = [NSString stringWithFormat:@"SELECT COUNT(DISTINCT groups) as Sum FROM Tasks"]; int sum; sqlite3_stmt *statement; if (sqlite3_prepare_v2( database, [groupquery UTF8String], -1, &statement, nil) == SQLITE_OK) { while (sqlite3_step(statement) == SQLITE_ROW) { sum = sqlite3_column_int(statement, 0); } sqlite3_finalize(statement); } if (sum=0) { return 1; } return 2; } I know I'm going wrong here but this is all that's in my numberOfRowsInSection method return [ids count];

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  • TraceTune shows Reads graphically

    - by Bill Graziano
    TraceTune now shows a graphical view of logical reads for each SQL statement in a trace file.  The width of the colored bar in the screen capture below is the percentage of logical reads for that statement.  The absolute number of reads is shown to the right. Any statement that has a user entered comment is shown in bold.  If you hover over the statement it will show the most recent comment for that statement.

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  • Ubuntu works in try out but not when installed, how to fix?

    - by QVaren
    I've got quite a problem with it, perhaps the problem lies with me but I thought I fixed it, I believe the opposite now... Anyhow, I started off with a 64-Bit Windows 7 platform and I wanted something new then the same boring windows, I heard about Ubuntu before but I didn't see a reason to change it. Now I had found my reason, so what did I do was do the installation via an USB, I went "try out before installation" first and it worked perfectly, however... When I installed it, deleted my Window 7 and tried to reboot with my fresh oh-so-clean new OS, it didn't want to load. At a certain point it said to boot up from a bootable option or something like that. Where it came to was that I couldn't load it up. Now, I wanted to switch back to Windows 7 because it didn't work and now I can't switch back because my harddrive switched modus because of Linux files (From NTFS to 4ex or something, I forgot). I'm currently typing this in the try out version of Ubuntu since I can't switch back to either Windows 7 or to the installed version of Ubuntu. So, my question follows: Can I fix it by keeping Ubuntu? Because I like Ubuntu. Also a side note: I'm a total noob when it comes down to this sort of things.

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  • Why does Alacarte give me this error when I try to add items to the menu?

    - by RichardoC
    When I try to add anything to the menu in 12.04 I get this error. $ alacarte Traceback (most recent call last): File "/usr/share/alacarte/Alacarte/MainWindow.py", line 317, in on_new_item_button_clicked process = subprocess.Popen(['gnome-desktop-item-edit', file_path], env=os.environ) File "/usr/lib/python2.7/subprocess.py", line 679, in __init__ errread, errwrite) File "/usr/lib/python2.7/subprocess.py", line 1249, in _execute_child raise child_exception OSError: [Errno 2] No such file or directory Thank you, R.C.

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  • Kernel panic - not syncing: no init found. Try passing init=option to kernel

    - by deepak
    I formatted all the partitions in my computer to a single ext4 partition and did a fresh installation of Ubuntu 13.04. I'm getting: Failed to execute /init Kernel panic - not syncing: no init found. Try passing init=option to kernel. Even on clean reinstall the issue persist. Booting from recovery mode leads to same error, so not able to reach the terminal. But able to boot from Live CD. Any help much appreciated.

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  • Assertion failure when trying to write (INSERT, UPDATE) to sqlite database on iPhone.

    - by Mark McFarlane
    I have a really frustrating error that I've spent hours looking at and cannot fix. I can get data from my db no problem with this code, but inserting or updating gives me these errors: *** Assertion failure in +[Functions db_insert_answer:question_type:score:], /Volumes/Xcode/Kanji/Classes/Functions.m:129 *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error inserting: db_insert_answer:question_type:score:' Here is the code I'm using: [Functions db_insert_answer:[[dict_question objectForKey:@"JISDec"] intValue] question_type:@"kanji_meaning" score:arc4random() % 100]; //update EF, Next_question, n here [Functions db_update_EF:[dict_question objectForKey:@"question"] EF:EF]; To call these functions: +(sqlite3_stmt *)db_query:(NSString *)queryText{ sqlite3 *database = [self get_db]; sqlite3_stmt *statement; NSLog(queryText); if (sqlite3_prepare_v2(database, [queryText UTF8String], -1, &statement, nil) == SQLITE_OK) { } else { NSLog(@"HMM, COULDNT RUN QUERY: %s\n", sqlite3_errmsg(database)); } sqlite3_close(database); return statement; } +(void)db_insert_answer:(int)obj_id question_type:(NSString *)question_type score:(int)score{ sqlite3 *database = [self get_db]; sqlite3_stmt *statement; char *errorMsg; char *update = "INSERT INTO Answers (obj_id, question_type, score, date) VALUES (?, ?, ?, DATE())"; if (sqlite3_prepare_v2(database, update, -1, &statement, nil) == SQLITE_OK) { sqlite3_bind_int(statement, 1, obj_id); sqlite3_bind_text(statement, 2, [question_type UTF8String], -1, NULL); sqlite3_bind_int(statement, 3, score); } if (sqlite3_step(statement) != SQLITE_DONE){ NSAssert1(0, @"Error inserting: %s", errorMsg); } sqlite3_finalize(statement); sqlite3_close(database); NSLog(@"Answer saved"); } +(void)db_update_EF:(NSString *)kanji EF:(int)EF{ sqlite3 *database = [self get_db]; sqlite3_stmt *statement; //NSLog(queryText); char *errorMsg; char *update = "UPDATE Kanji SET EF = ? WHERE Kanji = '?'"; if (sqlite3_prepare_v2(database, update, -1, &statement, nil) == SQLITE_OK) { sqlite3_bind_int(statement, 1, EF); sqlite3_bind_text(statement, 2, [kanji UTF8String], -1, NULL); } else { NSLog(@"HMM, COULDNT RUN QUERY: %s\n", sqlite3_errmsg(database)); } if (sqlite3_step(statement) != SQLITE_DONE){ NSAssert1(0, @"Error updating: %s", errorMsg); } sqlite3_finalize(statement); sqlite3_close(database); NSLog(@"Update saved"); } +(sqlite3 *)get_db{ sqlite3 *database; NSFileManager *fileManager = [NSFileManager defaultManager]; NSString *copyFrom = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"/kanji_training.sqlite"]; if([fileManager fileExistsAtPath:[self dataFilePath]]) { //NSLog(@"DB FILE ALREADY EXISTS"); } else { [fileManager copyItemAtPath:copyFrom toPath:[self dataFilePath] error:nil]; NSLog(@"COPIED DB TO DOCUMENTS BECAUSE IT DIDNT EXIST: NEW INSTALL"); } if (sqlite3_open([[self dataFilePath] UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to open database"); NSLog(@"FAILED TO OPEN DB"); } else { if([fileManager fileExistsAtPath:[self dataFilePath]]) { //NSLog(@"DB PATH:"); //NSLog([self dataFilePath]); } } return database; } + (NSString *)dataFilePath { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; return [documentsDirectory stringByAppendingPathComponent:@"kanji_training.sqlite"]; } I really can't work it out! Can anyone help me? Many thanks.

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  • MySql. What is there error on this insert+select+where statement?

    - by acidzombie24
    What is wrong with this statement? It works with sqlite and MS sql (last time i tested it) I would like a select unless there is no match with name or email. Then i would like to insert. I have it as one statement because its easy to keep concurrent safe as one statement. (its not that complex of a statement). INSERT INTO `user_data` ( `last_login_ip`, `login_date`, ...) SELECT @0, @14 WHERE not exists (SELECT * FROM `user_data` WHERE `name` = @15 OR `unconfirmed_email` = @16 LIMIT 1); Exception You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE not exists (SELECT * FROM `user_data` WHERE `name` = 'thename' OR `unconfirmed' at line 31

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  • PDOStatement::bindParam() not setting AI value from MySQL insert?

    - by Alan
    I have a simple insert statement using PDO php class. $statement = $db->prepare('INSERT INTO demographics (id,location_id,male,ethnicity_id,birthyear) VALUES (:id,:location_id,:male,:ethnicity_id,:birthyear)'); $statement->bindParam(':id',$demo->id,PDO::PARAM_INT,4); $statement->bindParam(':location_id', $demo->locationid,PDO::PARAM_INT); $statement->bindParam(':male',$demo->male,PDO::PARAM_BOOL); $statement->bindParam(':ethnicity_id',$demo->ethnicityid,PDO::PARAM_INT); $statement->bindParam(':birthyear',$demo->birthyear,PDO::PARAM_INT); $statement->execute(); print_r($demo); Even though the statement executes correctly (row is correctly written), $demo-id is null. Any thoughts?

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  • How to Fix "Read-only file system" error when I run something as sudo and try to make a folder/file?

    - by Andrew
    When I try to save something or rename a file/folder it say this error " Read-only file system" or run something as root in the terminal it say this error sudo: unable to open /var/lib/sudo/"My User Name"/0: Read-only file system W: Not using locking for read only lock file /var/lib/dpkg/lock E: Unable to write to /var/cache/apt/ E: The package lists or status file could not be parsed or opened. When I make a Folder the error dialog in the details with Nautilus is this: Error creating directory: Read-only file system I would show you I picture of it but it isn't even letting my save onto my flash drive. Please help me.

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  • Do we still have a case against the goto statement? [closed]

    - by FredOverflow
    Possible Duplicate: Is it ever worthwhile using goto? In a recent article, Andrew Koenig writes: When asked why goto statements are harmful, most programmers will say something like "because they make programs hard to understand." Press harder, and you may well hear something like "I don't really know, but that's what I was taught." For that reason, I'd like to summarize Dijkstra's arguments. He then shows two program fragments, one without a goto and and one with a goto: if (n < 0) n = 0; Assuming that n is a variable of a built-in numeric type, we know that after this code, n is nonnegative. Suppose we rewrite this fragment: if (n >= 0) goto nonneg; n = 0; nonneg: ; In theory, this rewrite should have the same effect as the original. However, rewriting has changed something important: It has opened the possibility of transferring control to nonneg from anywhere else in the program. I emphasized the part that I don't agree with. Modern languages like C++ do not allow goto to transfer control arbitrarily. Here are two examples: You cannot jump to a label that is defined in a different function. You cannot jump over a variable initialization. Now consider composing your code of tiny functions that adhere to the single responsibility principle: int clamp_to_zero(int n) { if (n >= 0) goto n_is_not_negative: n = 0; n_is_not_negative: return n; } The classic argument against the goto statement is that control could have transferred from anywhere inside your program to the label n_is_not_negative, but this simply is not (and was never) true in C++. If you try it, you will get a compiler error, because labels are scoped. The rest of the program doesn't even see the name n_is_not_negative, so it's just not possible to jump there. This is a static guarantee! Now, I'm not saying that this version is better then the one without the goto, but to make the latter as expressive as the first one, we would at least have to insert a comment, or even better yet, an assertion: int clamp_to_zero(int n) { if (n < 0) n = 0; // n is not negative at this point assert(n >= 0); return n; } Note that you basically get the assertion for free in the goto version, because the condition n >= 0 is already written in line 1, and n = 0; satisfies the condition trivially. But that's just a random observation. It seems to me that "don't use gotos!" is one of those dogmas like "don't use multiple returns!" that stem from a time where the real problem were functions of hundreds or even thousand of lines of code. So, do we still have a case against the goto statement, other than that it is not particularly useful? I haven't written a goto in at least a decade, but it's not like I was running away in terror whenever I encountered one. 1 Ideally, I would like to see a strong and valid argument against gotos that still holds when you adhere to established programming principles for clean code like the SRP. "You can jump anywhere" is not (and has never been) a valid argument in C++, and somehow I don't like teaching stuff that is not true. 1: Also, I have never been able to resurrect even a single velociraptor, no matter how many gotos I tried :(

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  • Using multiple A-records for my domain - do web browsers ever try more than one?

    - by Jonas
    If I add multiple A-records for my domain, they are returned in a round robin order by DNS-servers. E.g: 1.1.1.1 A example.com 1.1.1.2 A example.com 1.1.1.3 A example.com But how does webbrowsers react if the first host (1.1.1.1) is down (unreachable)? do they try the second host (1.1.1.2) or do they return a error message to the user? Are there any difference between the most popular browsers? If I implement my own application, I can implement so that the second is used in case the first is down, so it's possible. And this would be very helpful to create a fault tolerant website.

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  • Using multiple A-records for my domain - do web browsers ever try more than one?

    - by Jonas
    If I add multiple A-records for my domain, they are returned in a round robin order by DNS-servers. E.g: 1.1.1.1 A example.com 1.1.1.2 A example.com 1.1.1.3 A example.com But how does webbrowsers react if the first host (1.1.1.1) is down (unreachable)? do they try the second host (1.1.1.2) or do they return a error message to the user? Are there any difference between the most popular browsers? If I implement my own application, I can implement so that the second is used in case the first is down, so it's possible. And this would be very helpful to create a fault tolerant website.

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  • E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution)

    - by B Jo
    I would like to upgrade to Ubuntu 13.04 since almost a month now. Am a pretty novice in linux and in software in general. My /boot is full : bijo@bijo-AMILO-Xi-2428:~$ df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/ubuntu-root 228G 7.7G 208G 4% / udev 1001M 4.0K 1001M 1% /dev tmpfs 404M 836K 403M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1008M 156K 1008M 1% /run/shm none 100M 48K 100M 1% /run/user /dev/sda1 228M 222M 0 100% /boot I tried the : sudo apt-get purge $( dpkg --list | grep -P -o "linux-image-\d\S+" | grep -v $(uname -r | grep -P -o ".+\d") ) but i got this as reply E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution). infact I'm going round and round ... Can someone guide me through please? Thanks in advance for ur time

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  • Should I go with Android or Try Windows Phone 7?

    - by Omnion
    I already know C# and am familiar with XNA. So it would make sense to develop for the Windows Phone 7, but would it be worth while to learn Java, get familiar with Android, and instead develop for Android devices? Android has been around longer so it would probably have a larger user base. Is it really worth it to try to develop for one of the more popular mobile platforms. (Windows Phone 7 has been out for like a month?) I haven't tried either one yet though. I'm also going to buy a phone, so this decision would probably influence the phone that I buy. (to develop/test on)

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  • Why aren't variables declared in "try" in scope in "catch" or "finally"?

    - by Jon Schneider
    In C# and in Java (and possibly other languages as well), variables declared in a "try" block are not in scope in the corresponding "catch" or "finally" blocks. For example, the following code does not compile: try { String s = "test"; // (more code...) } catch { Console.Out.WriteLine(s); //Java fans: think "System.out.println" here instead } In this code, a compile-time error occurs on the reference to s in the catch block, because s is only in scope in the try block. (In Java, the compile error is "s cannot be resolved"; in C#, it's "The name 's' does not exist in the current context".) The general solution to this issue seems to be to instead declare variables just before the try block, instead of within the try block: String s; try { s = "test"; // (more code...) } catch { Console.Out.WriteLine(s); //Java fans: think "System.out.println" here instead } However, at least to me, (1) this feels like a clunky solution, and (2) it results in the variables having a larger scope than the programmer intended (the entire remainder of the method, instead of only in the context of the try-catch-finally). My question is, what were/are the rationale(s) behind this language design decision (in Java, in C#, and/or in any other applicable languages)?

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  • The Execute SQL Task

    In this article we are going to take you through the Execute SQL Task in SQL Server Integration Services for SQL Server 2005 (although it appies just as well to SQL Server 2008).  We will be covering all the essentials that you will need to know to effectively use this task and make it as flexible as possible. The things we will be looking at are as follows: A tour of the Task. The properties of the Task. After looking at these introductory topics we will then get into some examples. The examples will show different types of usage for the task: Returning a single value from a SQL query with two input parameters. Returning a rowset from a SQL query. Executing a stored procedure and retrieveing a rowset, a return value, an output parameter value and passing in an input parameter. Passing in the SQL Statement from a variable. Passing in the SQL Statement from a file. Tour Of The Task Before we can start to use the Execute SQL Task in our packages we are going to need to locate it in the toolbox. Let's do that now. Whilst in the Control Flow section of the package expand your toolbox and locate the Execute SQL Task. Below is how we found ours. Now drag the task onto the designer. As you can see from the following image we have a validation error appear telling us that no connection manager has been assigned to the task. This can be easily remedied by creating a connection manager. There are certain types of connection manager that are compatable with this task so we cannot just create any connection manager and these are detailed in a few graphics time. Double click on the task itself to take a look at the custom user interface provided to us for this task. The task will open on the general tab as shown below. Take a bit of time to have a look around here as throughout this article we will be revisting this page many times. Whilst on the general tab, drop down the combobox next to the ConnectionType property. In here you will see the types of connection manager which this task will accept. As with SQL Server 2000 DTS, SSIS allows you to output values from this task in a number of formats. Have a look at the combobox next to the Resultset property. The major difference here is the ability to output into XML. If you drop down the combobox next to the SQLSourceType property you will see the ways in which you can pass a SQL Statement into the task itself. We will have examples of each of these later on but certainly when we saw these for the first time we were very excited. Next to the SQLStatement property if you click in the empty box next to it you will see ellipses appear. Click on them and you will see the very basic query editor that becomes available to you. Alternatively after you have specified a connection manager for the task you can click on the Build Query button to bring up a completely different query editor. This is slightly inconsistent. Once you've finished looking around the general tab, move on to the next tab which is the parameter mapping tab. We shall, again, be visiting this tab throughout the article but to give you an initial heads up this is where you define the input, output and return values from your task. Note this is not where you specify the resultset. If however you now move on to the ResultSet tab this is where you define what variable will receive the output from your SQL Statement in whatever form that is. Property Expressions are one of the most amazing things to happen in SSIS and they will not be covered here as they deserve a whole article to themselves. Watch out for this as their usefulness will astound you. For a more detailed discussion of what should be the parameter markers in the SQL Statements on the General tab and how to map them to variables on the Parameter Mapping tab see Working with Parameters and Return Codes in the Execute SQL Task. Task Properties There are two places where you can specify the properties for your task. One is in the task UI itself and the other is in the property pane which will appear if you right click on your task and select Properties from the context menu. We will be doing plenty of property setting in the UI later so let's take a moment to have a look at the property pane. Below is a graphic showing our properties pane. Now we shall take you through all the properties and tell you exactly what they mean. A lot of these properties you will see across all tasks as well as the package because of everything's base structure The Container. BypassPrepare Should the statement be prepared before sending to the connection manager destination (True/False) Connection This is simply the name of the connection manager that the task will use. We can get this from the connection manager tray at the bottom of the package. DelayValidation Really interesting property and it tells the task to not validate until it actually executes. A usage for this may be that you are operating on table yet to be created but at runtime you know the table will be there. Description Very simply the description of your Task. Disable Should the task be enabled or not? You can also set this through a context menu by right clicking on the task itself. DisableEventHandlers As a result of events that happen in the task, should the event handlers for the container fire? ExecValueVariable The variable assigned here will get or set the execution value of the task. Expressions Expressions as we mentioned earlier are a really powerful tool in SSIS and this graphic below shows us a small peek of what you can do. We select a property on the left and assign an expression to the value of that property on the right causing the value to be dynamically changed at runtime. One of the most obvious uses of this is that the property value can be built dynamically from within the package allowing you a great deal of flexibility FailPackageOnFailure If this task fails does the package? FailParentOnFailure If this task fails does the parent container? A task can he hosted inside another container i.e. the For Each Loop Container and this would then be the parent. ForcedExecutionValue This property allows you to hard code an execution value for the task. ForcedExecutionValueType What is the datatype of the ForcedExecutionValue? ForceExecutionResult Force the task to return a certain execution result. This could then be used by the workflow constraints. Possible values are None, Success, Failure and Completion. ForceExecutionValue Should we force the execution result? IsolationLevel This is the transaction isolation level of the task. IsStoredProcedure Certain optimisations are made by the task if it knows that the query is a Stored Procedure invocation. The docs say this will always be false unless the connection is an ADO connection. LocaleID Gets or sets the LocaleID of the container. LoggingMode Should we log for this container and what settings should we use? The value choices are UseParentSetting, Enabled and Disabled. MaximumErrorCount How many times can the task fail before we call it a day? Name Very simply the name of the task. ResultSetType How do you want the results of your query returned? The choices are ResultSetType_None, ResultSetType_SingleRow, ResultSetType_Rowset and ResultSetType_XML. SqlStatementSource Your Query/SQL Statement. SqlStatementSourceType The method of specifying the query. Your choices here are DirectInput, FileConnection and Variables TimeOut How long should the task wait to receive results? TransactionOption How should the task handle being asked to join a transaction? Usage Examples As we move through the examples we will only cover in them what we think you must know and what we think you should see. This means that some of the more elementary steps like setting up variables will be covered in the early examples but skipped and simply referred to in later ones. All these examples used the AventureWorks database that comes with SQL Server 2005. Returning a Single Value, Passing in Two Input Parameters So the first thing we are going to do is add some variables to our package. The graphic below shows us those variables having been defined. Here the CountOfEmployees variable will be used as the output from the query and EndDate and StartDate will be used as input parameters. As you can see all these variables have been scoped to the package. Scoping allows us to have domains for variables. Each container has a scope and remember a package is a container as well. Variable values of the parent container can be seen in child containers but cannot be passed back up to the parent from a child. Our following graphic has had a number of changes made. The first of those changes is that we have created and assigned an OLEDB connection manager to this Task ExecuteSQL Task Connection. The next thing is we have made sure that the SQLSourceType property is set to Direct Input as we will be writing in our statement ourselves. We have also specified that only a single row will be returned from this query. The expressions we typed in was: SELECT COUNT(*) AS CountOfEmployees FROM HumanResources.Employee WHERE (HireDate BETWEEN ? AND ?) Moving on now to the Parameter Mapping tab this is where we are going to tell the task about our input paramaters. We Add them to the window specifying their direction and datatype. A quick word here about the structure of the variable name. As you can see SSIS has preceeded the variable with the word user. This is a default namespace for variables but you can create your own. When defining your variables if you look at the variables window title bar you will see some icons. If you hover over the last one on the right you will see it says "Choose Variable Columns". If you click the button you will see a list of checkbox options and one of them is namespace. after checking this you will see now where you can define your own namespace. The next tab, result set, is where we need to get back the value(s) returned from our statement and assign to a variable which in our case is CountOfEmployees so we can use it later perhaps. Because we are only returning a single value then if you remember from earlier we are allowed to assign a name to the resultset but it must be the name of the column (or alias) from the query. A really cool feature of Business Intelligence Studio being hosted by Visual Studio is that we get breakpoint support for free. In our package we set a Breakpoint so we can break the package and have a look in a watch window at the variable values as they appear to our task and what the variable value of our resultset is after the task has done the assignment. Here's that window now. As you can see the count of employess that matched the data range was 2. Returning a Rowset In this example we are going to return a resultset back to a variable after the task has executed not just a single row single value. There are no input parameters required so the variables window is nice and straight forward. One variable of type object. Here is the statement that will form the soure for our Resultset. select p.ProductNumber, p.name, pc.Name as ProductCategoryNameFROM Production.ProductCategory pcJOIN Production.ProductSubCategory pscON pc.ProductCategoryID = psc.ProductCategoryIDJOIN Production.Product pON psc.ProductSubCategoryID = p.ProductSubCategoryID We need to make sure that we have selected Full result set as the ResultSet as shown below on the task's General tab. Because there are no input parameters we can skip the parameter mapping tab and move straight to the Result Set tab. Here we need to Add our variable defined earlier and map it to the result name of 0 (remember we covered this earlier) Once we run the task we can again set a breakpoint and have a look at the values coming back from the task. In the following graphic you can see the result set returned to us as a COM object. We can do some pretty interesting things with this COM object and in later articles that is exactly what we shall be doing. Return Values, Input/Output Parameters and Returning a Rowset from a Stored Procedure This example is pretty much going to give us a taste of everything. We have already covered in the previous example how to specify the ResultSet to be a Full result set so we will not cover it again here. For this example we are going to need 4 variables. One for the return value, one for the input parameter, one for the output parameter and one for the result set. Here is the statement we want to execute. Note how much cleaner it is than if you wanted to do it using the current version of DTS. In the Parameter Mapping tab we are going to Add our variables and specify their direction and datatypes. In the Result Set tab we can now map our final variable to the rowset returned from the stored procedure. It really is as simple as that and we were amazed at how much easier it is than in DTS 2000. Passing in the SQL Statement from a Variable SSIS as we have mentioned is hugely more flexible than its predecessor and one of the things you will notice when moving around the tasks and the adapters is that a lot of them accept a variable as an input for something they need. The ExecuteSQL task is no different. It will allow us to pass in a string variable as the SQL Statement. This variable value could have been set earlier on from inside the package or it could have been populated from outside using a configuration. The ResultSet property is set to single row and we'll show you why in a second when we look at the variables. Note also the SQLSourceType property. Here's the General Tab again. Looking at the variable we have in this package you can see we have only two. One for the return value from the statement and one which is obviously for the statement itself. Again we need to map the Result name to our variable and this can be a named Result Name (The column name or alias returned by the query) and not 0. The expected result into our variable should be the amount of rows in the Person.Contact table and if we look in the watch window we see that it is.   Passing in the SQL Statement from a File The final example we are going to show is a really interesting one. We are going to pass in the SQL statement to the task by using a file connection manager. The file itself contains the statement to run. The first thing we are going to need to do is create our file connection mananger to point to our file. Click in the connections tray at the bottom of the designer, right click and choose "New File Connection" As you can see in the graphic below we have chosen to use an existing file and have passed in the name as well. Have a look around at the other "Usage Type" values available whilst you are here. Having set that up we can now see in the connection manager tray our file connection manager sitting alongside our OLE-DB connection we have been using for the rest of these examples. Now we can go back to the familiar General Tab to set up how the task will accept our file connection as the source. All the other properties in this task are set up exactly as we have been doing for other examples depending on the options chosen so we will not cover them again here.   We hope you will agree that the Execute SQL Task has changed considerably in this release from its DTS predecessor. It has a lot of options available but once you have configured it a few times you get to learn what needs to go where. We hope you have found this article useful.

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  • SQLITE crash when no data present in table

    - by johnblack45
    Hey, Im having a problem with my app that causes it to crash when no data is present in the table when using a table view. I have tested my code and it works fine as long as there is data present but i need it to work when there is no data present. -(void)initialiseTableData { NSMutableArray *array = [[NSMutableArray alloc]init]; sqlite3 *db = [iCaddyAppDelegate getNewDBConnection]; sqlite3_stmt *statement; const char *sql = "select courseId, courseName, totalPar, totalyardage, holePars, holeYardages, holeStrokeIndexs from Course"; if(sqlite3_prepare_v2(db, sql, -1, &statement, NULL)!= SQLITE_OK) { NSAssert1(0,@"Error preparing statement",sqlite3_errmsg(db)); sqlite3_close(db); } else { while (sqlite3_step(statement) == SQLITE_ROW) { Course *temp = [[Course alloc]init]; temp.courseId = sqlite3_column_int(statement,0); temp.courseName = [NSString stringWithFormat:@"%s",(char*)sqlite3_column_text(statement,1)]; temp.totalPar =sqlite3_column_int(statement,2); temp.totalYardage =sqlite3_column_int(statement,3); NSString tempHolePars = [NSString stringWithFormat:@"%s",(char)sqlite3_column_text(statement,4)]; NSString tempHoleYardages = [NSString stringWithFormat:@"%s",(char)sqlite3_column_text(statement,5)]; NSString tempHoleStrokeIndexes = [NSString stringWithFormat:@"%s",(char)sqlite3_column_text(statement,6)]; NSArray *temp1 = [tempHolePars componentsSeparatedByString:@":"]; NSArray *temp2 = [tempHoleYardages componentsSeparatedByString:@":"]; NSArray *temp3 = [tempHoleStrokeIndexes componentsSeparatedByString:@":"]; for(int i = 0; i<=17; i++) { NSString *temp1String = [temp1 objectAtIndex:i]; [temp.holePars insertObject:temp1String atIndex:i]; NSString *temp2String = [temp2 objectAtIndex:i]; [temp.holeYardages insertObject:temp2String atIndex:i]; NSString *temp3String = [temp3 objectAtIndex:i]; [temp.holeStrokeIndexes insertObject:temp3String atIndex:i]; } [array addObject:temp]; } self.list = array; [self.table reloadData]; } }

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  • Grub menu will not show the first time I try to boot my ubuntu server 12.04 after it is shutdown for a long time

    - by user211477
    I am running into a booting issue after installing Ubuntu Server 12.04 LTS. Following is the symptom of the problem. SYSTEM DESCRIPTION: Dual core AMD Athlon 64 3 Disks: two SATA (out of which one is SSD) and one PATA. Using LVM for disk partition management. /boot is not under LVM rest of the partitions are. / is on the SSD BIOS boot sequence is correct and points to the disk with /boot and boot loader is installed on this disk. SYMPTOMS: POST messages Blinking cursor on first line then moves to second line Screen flickers then becomes black Everything is unresponsive, hard reboot POST messages will not show up on screen. Monitor displays powersave message Force shutdown machine again. Shutoff power to machine for a few minutes. Restart machine. POST message show up. Grub menu shows up Ubuntu server 12.04 boots normally. From now on Ubuntu server boots normally until machine is shutdown for a long time (for example, 30 mins) Repeat steps 1 through 13 once the machine is started after a long time. WHAT DID I TRY? I read several posts and have tried: radeon.modeset=0 setting the gfxmode edd=0 nolacpi boot-repair Nothing seems to work. In my search I did see only one post with this same symptom. Unfortunately, I am not being able to locate that post anymore. The interesting fact is that with this same machine configuration, if I install Ubuntu Desktop 12.04 then everything works fine. Any help will be appreciated.

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