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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • @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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  • What's the right way to handle "One, Both, or None" logic?

    - by Stephen
    I have a logic situation that is best described as two "Teams" trying to win a task. The outcome of this task could be a single winner, a tie (draw), or no winner (stalemate). Currently, I'm using a nested if/else statement like so: // using PHP, but the concept seems language agnostic. if ($team_a->win()) { if ($team_b->win()) { // this is a draw } else { // team_a is the winner } } else { if ($team_b->win()) { // team_b is the winner } else { // This is a stalemate, no winner. } } This seems rather spaghetti-like and repetitive. Is there a more logical, DRY pattern I could use?

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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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  • why my array is losing it's contents when I refresh the page?

    - by Fernando SBS
    I have created an: var checkboxFarm = new Array(); then I want to record a checkbox status in that array, as there are 11 checkboxes. Button.addEventListener("click", function() { rp_farmAtivada(index); }, false); when clicked change the variable in the array: function rp_farmAtivada(index) { checkboxFarm[index] = !checkboxFarm[index]; }; but every time I refresh the page it loses all the checkboxes status and I'm aware that all that array gets the "undefined" value. the checkboxFarm array is defined in the beginning of the script, so it should have a global scope. Am I missing something?

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  • How to determine if CNF formula is satisfiable in Scheme?

    - by JJBIRAN
    Program a SCHEME function sat that takes one argument, a CNF formula represented as above. If we had evaluated (define cnf '((a (not b) c) (a (not b) (not d)) (b d))) then evaluating (sat cnf) would return #t, whereas (sat '((a) (not a))) would return (). You should have following two functions to work: (define comp (lambda (lit) ; This function takes a literal as argument and returns the complement literal as the returning value. Examples: (comp 'a) = (not a), and (comp '(not b)) = b. (define consistent (lambda (lit path) This function takes a literal and a list of literals as arguments, and returns #t whenever the complement of the first argument is not a member of the list represented by the 2nd argument; () otherwise. . Now for the sat function. The real searching involves the list of clauses (the CNF formula) and the path that has currently been developed. The sat function should merely invoke the real "workhorse" function, which will have 2 arguments, the current path and the clause list. In the initial call, the current path is of course empty. Hints on sat. (Ignore these at your own risk!) (define sat (lambda (clauselist) ; invoke satpath (define satpath (lambda (path clauselist) ; just returns #t or () ; base cases: ; if we're out of clauses, what then? ; if there are no literals to choose in the 1st clause, what then? ; ; then in general: ; if the 1st literal in the 1st clause is consistent with the ; current path, and if << returns #t, ; then return #t. ; ; if the 1st literal didn't work, then search << ; the CNF formula in which the 1st clause doesn't have that literal Don't make this too hard. My program is a few functions averaging about 2-8 lines each. SCHEME is consise and elegant! The following expressions may help you to test your programs. All but cnf4 are satisfiable. By including them along with your function definitions, the functions themselves are automatically tested and results displayed when the file is loaded. (define cnf1 '((a b c) (c d) (e)) ) (define cnf2 '((a c) (c))) (define cnf3 '((d e) (a))) (define cnf4 '( (a b) (a (not b)) ((not a) b) ((not a) (not b)) ) ) (define cnf5 '((d a) (d b c) ((not a) (not d)) (e (not d)) ((not b)) ((not d) (not e)))) (define cnf6 '((d a) (d b c) ((not a) (not d) (not c)) (e (not c)) ((not b)) ((not d) (not e)))) (write-string "(sat cnf1) ") (write (sat cnf1)) (newline) (write-string "(sat cnf2) ") (write (sat cnf2)) (newline) (write-string "(sat cnf3) ") (write (sat cnf3)) (newline) (write-string "(sat cnf4) ") (write (sat cnf4)) (newline) (write-string "(sat cnf5) ") (write (sat cnf5)) (newline)

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  • Database schema to store AND, OR relation, association

    - by user455387
    Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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  • Python `if x is not None` or `if not x is None`?

    - by orokusaki
    I've always thought of the if not x is None version to be more clear, but Google's style guide implies (based on this excerpt) that they use if x is not None. Is there any minor performance difference (I'm assuming not), and is there any case where one really doesn't fit (making the other a clear winner for my convention)?* *I'm referring to any singleton, rather than just None. ...to compare singletons like None. Use is or is not.

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  • Python 3 order of testing undetermined

    - by user578598
    string='a' p=0 while (p <len(string)) & (string[p]!='c') : p +=1 print ('the end but the process already died ') while (p <1) & (string[p]!='c') : IndexError: string index out of range I want to test a condition up to the end of a string (example string length=1) why are both parts of the and executed is the condition is already false! as long as p < len(string). the second part does not even need executing. if it does a lot of performance can be lost

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  • fastest method for minimum of two numbers

    - by user85030
    I was going through mit's opencourseware related to performance engineering. The quickest method (requiring least number of clock cycles) for finding the minimum of two numbers(say x and y) is stated as: min= y^((x^y) & -(x<y)) The output of the expression x < y can be 0 or 1 (assuming C is being used) which then changes to -0 or -1. I understand that xor can be used to swap two numbers. Questions: 1. How is -0 different from 0 and -1 in terms of binary? 2. How is that result used with the and operator to get the minimum? Thanks in advance.

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  • How can I use && in if in Ruby on Rails?

    - by Angela
    I tried the following && conditional for my if statement and I get a "bad range" error: <% if (from_today(contact, call.days) == 0..7) && (show_status(contact, call) == 'no status') %> Why and how can I fix it? The only other way I could do it was to have a second nested if statement and break it apart...not pretty :(

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