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• SQL: Return "true" if list of records exists?

  - by User

  An alternative title might be: Check for existence of multiple rows? Using a combination of SQL and C# I want a method to return true if all products in a list exist in a table. If it can be done in all in SQL that would be preferable. I have written a method that returns whether a single productID exists using the following SQL: SELECT productID FROM Products WHERE ProductID = @productID If this returns a row, then the c# method returns true, false otherwise. Now I'm wondering if I have a list of product IDs (not a huge list mind you, normally under 20). How can I write a query that will return a row if all the product id's exist and no row if one or more product id's does not exist? (Maybe something involving "IN" like: SELECT * FROM Products WHERE ProductID IN (1, 10, 100))

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• Objective-C : BOOL vs bool

  - by santoni

  Hi, I'm new to objective-c and I saw the "new type" BOOL (YES, NO). I read that this type is almost like a char. For testing I did : NSLog(@"Size of BOOL %d", sizeof(BOOL)); NSLog(@"Size of bool %d", sizeof(bool)); Good to see both display 1 (sometimes in C++ bool just an int and sizeof is 4) So I was just wondering I there were some issues with the bool type or something ? Can I just use bool (that seems to work) without loosing speed? Thanks for answers

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• error C2440: '=' : cannot convert from 'bool' to 'bool *'

  - by William

  I'm getting said error on this line "b = true". Now Why am I getting this error? Aren't I pointing to TurnMeOn and thus saying TurnMeOn = true? class B{ void turnOn(bool *b){b = true} }; int main(){ B *b = new B(); bool turnMeOn = false; b->turnOn(&turnMeOn); cout << "b = " << turnMeOn << endl; }

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• Static analysis of multiple if statements (conditions)

  - by koppernickus

  I have code similar to: if conditionA(x, y, z) then doA() else if conditionB(x, y, z) then doB() ... else if conditionZ(x, y, z) then doZ() else throw ShouldNeverHappenException I would like to validate two things (using static analysis): If all conditions conditionA, conditionB, ..., conditionZ are mutually exclusive (i.e. it is not possible that two or more conditions are true in the same time). All possible cases are covered, i.e. "else throw" statement will never be called. Could you recommend me a tool and/or a way I could (easily) do this? I would appreciate more detailed informations than "use Prolog" or "use Mathematica"... ;-)

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• Strange error in ASP.NET

  - by rockinthesixstring

  Every once in a while I get about 10 - 20 identical errors on my asp.net app. It's always the same, and I'm wondering if it is someone trying to hack in (it happens about once a month). Source: System.Web Message: The file '/~/Default.aspx' does not exist. User IP: 89.122.29.80 User Browser: Unknown 0.0 User OS: Unknown Stack trace: at System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) at System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean completedSynchronously) why on earth would someone be trying to access "/~/Default.aspx" ?

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• What does !! (double exclamation point) mean?

  - by molecules

  In the code below, from a blog post by Alias, I noticed the use of the double exclamation point !!. I was wondering what it meant and where I could go in the future to find explanations for Perl syntax like this. (Yes, I already searched for '!!' at perlsyn). package Foo; use vars qw{$DEBUG}; BEGIN { $DEBUG = 0 unless defined $DEBUG; } use constant DEBUG => !! $DEBUG; sub foo { debug('In sub foo') if DEBUG; ... } UPDATE Thanks for all of your answers. Here is something else I just found that is related The List Squash Operator x!!

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• missing value true / false: error in loop not in one-off

  - by vincent hay

  I am new on R and I have a problem with a test in a loop that I want to code. With a data frame (tabetest) like the one here after: Date 25179M103 1 14977 77.7309 2 14978 77.2567 3 14979 77.7507 I have: if(tabetest[3,"Date"]-tabetest[1,"Date"]1){print("ok")} [1] "ok" But: j=1 > position = 1 > price=tabetest for (i in 1:nrow(tabetest)-position){if(tabetest[i+position,"Date"]-tabetest[position,"Date"]>20){price[i+position,j]=price[i+position,j]/price[position,j]-1};position=position+1} Returns an error. R says that there is a missing value where true/false is required in: if (tabetest[i + position, "Date"] - tabetest[position, "Date"] > I have spent quite some time on that error but still don't understand where it comes from. Thanks for your help, Vincent

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• If I XOR 2 numbers, do I only get identical results if the numbers are the same?

  - by they changed my name

  For example, suppose I have x XOR y = y XOR x = z. Is it possible to have something like a XOR b = z?

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• How do I call a static bool method in main.m

  - by AaronG

  This is Objective-C, in Xcode for the iPhone. I have a method in main.m: int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; //I want to call the method here// int retVal = UIApplicationMain(argc, argv, nil, nil); [pool release]; return retVal; } static BOOL do_it_all () { //code here// } How do I call the do_it_all method from main.m?

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• How to organize infinite while loop in SQL Server ?

  - by alpav

  I want to use infinite WHILE loop in SQL Server 2005 and use BREAK keyword to exit from it on certain condition. while true does not work, so I have to use while 1=1. Is there a better way to organize infinite loop ? I know that I can use goto, but while 1=1 begin .. end looks better structurally.

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• Why overload true and false instead of defining bool operator?

  - by Joe Enos

  I've been reading about overloading true and false in C#, and I think I understand the basic difference between this and defining a bool operator. The example I see around is something like: public static bool operator true(Foo foo) { return (foo.PropA > 0); } public static bool operator false(Foo foo) { return (foo.PropA <= 0); } To me, this is the same as saying: public static implicit operator bool(Foo foo) { return (foo.PropA > 0); } The difference, as far as I can tell, is that by defining true and false separately, you can have an object that is both true and false, or neither true nor false: public static bool operator true(Foo foo) { return true; } public static bool operator false(Foo foo) { return true; } //or public static bool operator true(Foo foo) { return false; } public static bool operator false(Foo foo) { return false; } I'm sure there's a reason this is allowed, but I just can't think of what it is. To me, if you want an object to be able to be converted to true or false, a single bool operator makes the most sense. Can anyone give me a scenario where it makes sense to do it the other way? Thanks

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• Why am I getting such random results when checking DNS?

  - by animuson

  The code is as follows: $domain = "fosajfjdkgdajfhsd.com"; $check1 = checkdnsrr($domain, "MX"); $check2 = checkdnsrr($domain, "A"); $check3 = (checkdnsrr($domain, "MX") || checkdnsrr($domain, "A")); $check4 = !(checkdnsrr($domain, "MX") || checkdnsrr($domain, "A")); die("{$check1} - {$check2} - {$check3} - {$check4}"); However when I check the output to see what it's returning, I get this: - 1 - 1 - The domain obviously wouldn't exist, so I don't understand why checking the A record is return true and checking the MX result doesn't give me anything at all. I don't understand what's going wrong here.

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• How can I build a Truth Table Generator?

  - by KingNestor

  I'm looking to write a Truth Table Generator as a personal project. There are several web-based online ones here and here. (Example screenshot of an existing Truth Table Generator) I have the following questions: How should I go about parsing expressions like: ((P = Q) & (Q = R)) = (P = R) Should I use a parser generator like ANTLr or YACC, or use straight regular expressions? Once I have the expression parsed, how should I go about generating the truth table? Each section of the expression needs to be divided up into its smallest components and re-built from the left side of the table to the right. How would I evaluate something like that? Can anyone provide me with tips concerning the parsing of these arbitrary expressions and eventually evaluating the parsed expression?

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• Logical equality in C

  - by andrew cooke

  [It seems odd this doesn't exist, so apologies in advance if it's a duplicate] I want to test for logical equality in C. In other words, I want to know whether two values would be equal if both were converted in the normal way associated with logical expressions. In C99, I think that (bool)a == (bool)b gives what I want. Is that correct? What is the normal way of writing this in traditional C?

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• Optimize conditional operators branching in C#

  - by abatishchev

  Hello. I have next code: return this.AllowChooseAny.Value ? radioSpecific.Checked ? UserManager.CurrentUser.IsClient ? txtSubject.Text : subjectDropDownList.SelectedItem.Text : String.Empty : UserManager.CurrentUser.IsClient ? txtSubject.Text : subjectDropDownList.SelectedItem.Text; or in less complex form: return any ? specified ? isClient ? textbox : dropdown : empty : isClient ? textbox : dropdown; or in schematic form: | any / \ specified isClient / \ / \ isClient empty textbox dropdown / \ textbox dropdown Evidently I have a duplicated block on two different levels. Is it possible to optimize this code to probably split them to one? Or something like that..

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• How to organize infinite while loop in mssql ?

  - by alpav

  I want to use infinite WHILE loop in SQL 2005 and use BREAK keyword to exit from it on certain condition. while true does not work, so I have to use while 1=1. Is there a better way to organize infinite loop ? I know that I can use goto, but while 1=1 begin .. end looks better structurally.

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• Converting an empty string into nil in Ruby

  - by adi92

  I have a string called word and a function called infinitive such that word.infinitive would return another string on some occasions and an empty string otherwise I am trying to find an elegant ruby one line expression for the code-snippet below if word.infinitive == "" return word else return word.infinitive Had infinitive returned nil instead of "", I could have done something like (word.infinitive or word) But since it does not, I can't take advantage of the short-circuit OR Ideally I would want 1) a single expression that I could easily embed in other code 2) the function infinitive being called only once 3) to not add any custom gems or plugins into my code

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• Writing booleans to file

  - by Sara

  Hello, I have a piece of code that gives a runtime error. Can anyone help find out why? vector<int> intData; vector<bool> boolData; for(int i=0;i<19000;i++) boolData.push_back(false); string ofile = "tree.dat"; ofstream fout(ofile.c_str(),ios::out | ios::binary); if (!boolData.empty()) fout.write((char *)&boolData[0], sizeof(bool)*boolData.size()); fout.close(); It gives the error when it tries to write the file (fout.write).

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• How to access a list in OCaml

  - by Erik

  I want to write a function that could check every item in a list is true or false. If at least one element is false, it will return true, so that: assert_eq "checkFalse [true; false; true]" (checkFalse [true; true; true]) false; assert_eq "checkFalse [false; false]" (checkFalse [false; true]) true; I am an absolute beginner in OCaml and I don't know how to approach this. I tried using a for loop, something like: let rec checkFalse (bools: bool list) : bool = for i = 0 to bools.length do if bools.length == false then false else... (I don't know how to continue) Then it said "Unbound record field...." I also tried using find like: if (find false bools != Not_found) then true else false But my ways did not work. I came from a Java background. Thank you very much!

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• Nhibernate.Bytecode.Castle Trust Level on IIS

  - by jack london

  Trying to deploy the wcf service, depended on nhibernate. And getting the following exception On Reflection activator. [SecurityException: That assembly does not allow partially trusted callers.] System.Security.CodeAccessSecurityEngine.ThrowSecurityException(Assembly asm, PermissionSet granted, PermissionSet refused, RuntimeMethodHandle rmh, SecurityAction action, Object demand, IPermission permThatFailed) +150 System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 NHibernate.Bytecode.ActivatorObjectsFactory.CreateInstance(Type type) +8 NHibernate.Driver.ReflectionBasedDriver.CreateConnection() +28 NHibernate.Connection.DriverConnectionProvider.GetConnection() +56 NHibernate.Tool.hbm2ddl.SchemaExport.Execute(Action`1 scriptAction, Boolean export, Boolean justDrop) +376 in IIS configuration service's trust level is Full-trust also application's web config's trust level is full. how could i make this service in working state?

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• Instance Failure in asp.net

  - by user85511

  I have a web application that is working perfectly in my system. However, when I copied it to another system, I couldn't login to the application. There is an error: Server Error in '/' Application. -------------------------------------------------------------------------------- Instance failure. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: Instance failure. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [InvalidOperationException: Instance failure.] System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject) +4858423 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +90 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +257 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +221 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +189 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +4859187 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +31 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +433 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +499 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 System.Web.DataAccess.SqlConnectionHolder.Open(HttpContext context, Boolean revertImpersonate) +87 System.Web.DataAccess.SqlConnectionHelper.GetConnection(String connectionString, Boolean revertImpersonation) +221 System.Web.Security.SqlMembershipProvider.GetPasswordWithFormat(String username, Boolean updateLastLoginActivityDate, Int32& status, String& password, Int32& passwordFormat, String& passwordSalt, Int32& failedPasswordAttemptCount, Int32& failedPasswordAnswerAttemptCount, Boolean& isApproved, DateTime& lastLoginDate, DateTime& lastActivityDate) +815 System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved, String& salt, Int32& passwordFormat) +105 System.Web.Security.SqlMembershipProvider.CheckPassword(String username, String password, Boolean updateLastLoginActivityDate, Boolean failIfNotApproved) +42 System.Web.Security.SqlMembershipProvider.ValidateUser(String username, String password) +78 System.Web.UI.WebControls.Login.AuthenticateUsingMembershipProvider(AuthenticateEventArgs e) +60 System.Web.UI.WebControls.Login.OnAuthenticate(AuthenticateEventArgs e) +119 System.Web.UI.WebControls.Login.AttemptLogin() +115 System.Web.UI.WebControls.Login.OnBubbleEvent(Object source, EventArgs e) +101 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +118 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +166 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 -------------------------------------------------------------------------------- Version Information: Microsoft .NET Framework Version:2.0.50727.3053; ASP.NET Version:2.0.50727.3053 What could be the reason for such an error? How could I solve this?

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• Why 0 is true but false is 1 in bash?

  - by httpinterpret

  false; echo $? The above will output 1,which is contradictory with all other programming languages I know. Any reason in this?

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• NSArray filled with bool objects

  - by Matt S.

  I have an NSArray filled with bool objects (expressed as a number), and I need to test to see if any object within the array is equal to 1. How can I do it?

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• @property setter for BOOL.

  - by George

  Hi, I'm having problems setting a BOOL using @property and @synthesize. I'm using @property BOOL isPaused; And I can get it by using [myObject isPaused]; but I cannot manage to set it. I'd like to use [myObject setPaused: NO];. I also tried @property (setter=setPaused) BOOL isPaused; but if I'm not mistaking, then I need to write that setter myself.

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• How do "and" and "or" work when combined in one statement?

  - by orokusaki

  For some reason this function confused me: def protocol(port): return port == "443" and "https://" or "http://" Can somebody explain the order of what's happening behind the scenes to make this work the way it does. I understood it as this until I tried it: Either A) def protocol(port): if port == "443": if bool("https://"): return True elif bool("http://"): return True return False Or B) def protocol(port): if port == "443": return True + "https://" else: return True + "http://" Is this some sort of special case in Python, or am I completely misunderstanding how statements work?

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