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• Build and test on 2.2.1 iPod Touch with XCode 3.2.2?

  - by slewis

  I've just installed Xcode 3.2.2 with iPhone SDK 3.2 Beta 5 (Snow Leopard) This version of Xcode didn't come with any iPhone SDKs older than 3.0. But I want to create an app that runs on all devices from iPhone OS 2.2.1 - 3.1.3. I managed to add older SDKs into Xcode by downloading iPhone 3.1.3 with Xcode 3.1.4 and installing each 2.x SDK from the 'Packages' folder in the .dmg. So now I can select 2.2.1 as 'iPhone OS Deployment Target' and the 'Base SDK' as 3.1.3, and the app will build (thus letting me use 3.1.3 APIs with conditional coding whilst still running on 2.2.1 devices). But the problem is the app will not install and run on my 2.2.1 iPod Touch. Instead, Xcode tells me 'No provisioned iPhone OS device is connected'. If I bring up the Organizer, in the left column, the iPod Touch has an orange sphere next to it, instead of green, and clicking on this reveals: 'The version of iPhone OS on “iPod touch” is too old for use with this version of the iPhone SDK. Please restore the device to a version of the OS listed below' I'm not sure how to get this version of the SDK to support 2.2.1. (It needs to be this download of XCode/iPhone SDK because I also want it to be a universal binary so it runs on the iPad with a minimum of fuss).

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• .NET Regex - Replace multiple characters at once without overwriting?

  - by Everaldo Aguiar

  I'm implementing a c# program that should automatize a Mono-alphabetic substitution cipher. The functionality i'm working on at the moment is the simplest one: The user will provide a plain text and a cipher alphabet, for example: Plain text(input): THIS IS A TEST Cipher alphabet: A - Y, H - Z, I - K, S - L, E - J, T - Q Cipher Text(output): QZKL KL QJLQ I thought of using regular expressions since I've been programming in perl for a while, but I'm encountering some problems on c#. First I would like to know if someone would have a suggestion for a regular expression that would replace all occurrence of each letter by its corresponding cipher letter (provided by user) at once and without overwriting anything. Example: In this case, user provides plaintext "TEST", and on his cipher alphabet, he wishes to have all his T's replaced with E's, E's replaced with Y and S replaced with J. My first thought was to substitute each occurrence of a letter with an individual character and then replace that character by the cipherletter corresponding to the plaintext letter provided. Using the same example word "TEST", the steps taken by the program to provide an answer would be: 1 - replace T's with (lets say) @ 2 - replace E's with # 3 - replace S's with & 4 - Replace @ with E, # with Y, & with j 5 - Output = EYJE This solution doesn't seem to work for large texts. I would like to know if anyone can think of a single regular expression that would allow me to replace each letter in a given text by its corresponding letter in a 26-letter cipher alphabet without the need of splitting the task in an intermediate step as I mentioned. If it helps visualize the process, this is a print screen of my GUI for the program:

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• Parsing HTTP - Bytes.length != String.length

  - by hotzen

  Hello, I consume HTTP via nio.SocketChannel, so I get chunks of data as Array[Byte]. I want to put these chunks into a parser and continue parsing after each chunk has been put. HTTP itself seems to use an ISO8859-Charset but the Payload/Body itself may be arbitrarily encoded: If the HTTP Content-Length specifies X bytes, the UTF8-decoded Body may have much less Characters (1 Character may be represented in UTF8 by 2 bytes, etc). So what is a good parsing strategy to honor an explicitly specified Content-Length and/or a Transfer-Encoding: Chunked which specifies a chunk-length to be honored. append each data-chunk to an mutable.ArrayBuffer[Byte], search for CRLF in the bytes, decode everything from 0 until CRLF to String and match with Regular-Expressions like StatusRegex, HeaderRegex, etc? decode each data-chunk with the proper charset (e.g. iso8859, utf8, etc) and add to StringBuilder. With this solution I am not able to honor any Content-Length or Chunk-Size, but.. do I have to care for it? any other solution... ?

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• Is there unreachable code in this snippet? I don't think so, but Resharper is telling me otherwise.

  - by The Matt

  I have the following method I came across in a code review. Inside the loop Resharper is telling me that if (narrativefound == false) is incorrect becuase narrativeFound is always true. I don't think this is the case, because in order to set narrativeFound to true it has to pass the conditional string compare first, so how can it always be true? Am I missing something? Is this a bug in Resharper or in our code? public Chassis GetChassisForElcomp(SPPA.Domain.ChassisData.Chassis asMaintained, SPPA.Domain.ChassisData.Chassis newChassis) { Chassis c = asMaintained; List<Narrative> newNarrativeList = new List<Narrative>(); foreach (Narrative newNarrative in newChassis.Narratives) { bool narrativefound = false; foreach (Narrative orig in asMaintained.Narratives) { if (string.Compare(orig.PCode, newNarrative.PCode) ==0 ) { narrativefound = true; if (newNarrative.NarrativeValue.Trim().Length != 0) { orig.NarrativeValue = newNarrative.NarrativeValue; newNarrativeList.Add(orig); } break; } if (narrativefound == false) { newNarrativeList.Add(newNarrative); } } } c.SalesCodes = newChassis.SalesCodes; c.Narratives = newNarrativeList; return c; }

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• Use Javascript RegEx to extract column names from SQLite Create Table SQL

  - by NimbusSoftware

  I'm trying to extract column names from a SQLite result set from sqlite_master's sql column. I get hosed up in the regular expressions in the match() and split() functions. t1.executeSql('SELECT name, sql FROM sqlite_master WHERE type="table" and name!="__WebKitDatabaseInfoTable__";', [], function(t1, result) { for(i = 0;i < result.rows.length; i++){ var tbl = result.rows.item(i).name; var dbSchema = result.rows.item(i).sql; // errors out on next line var columns = dbSchema.match(/.*CREATE\s+TABLE\s+(\S+)\s+\((.*)\).*/)[2].split(/\s+[^,]+,?\s*/); } }, function(){console.log('err1');} ); I want to parse SQL statements like these... CREATE TABLE sqlite_sequence(name,seq); CREATE TABLE tblConfig (Key TEXT NOT NULL,Value TEXT NOT NULL); CREATE TABLE tblIcon (IconID INTEGER NOT NULL PRIMARY KEY,png TEXT NOT NULL,img32 TEXT NOT NULL,img64 TEXT NOT NULL,Version TEXT NOT NULL) into a strings like theses... name,seq Key,Value IconID,png,img32,img64,Version Any help with a RegEx would be greatly appreciated.

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• Using PHP as template language

  - by Kunal

  I wrote up this quick class to do templating via PHP -- I was wondering if this is easily exploitable if I were ever to open up templating to users (not the immediate plan, but thinking down the road). class Template { private $allowed_methods = array( 'if', 'switch', 'foreach', 'for', 'while' ); private function secure_code($template_code) { $php_section_pattern = '/\<\?(.*?)\?\>/'; $php_method_pattern = '/([a-zA-Z0-9_]+)[\s]*\(/'; preg_match_all($php_section_pattern, $template_code, $matches); foreach (array_unique($matches[1]) as $index => $code_chunk) { preg_match_all($php_method_pattern, $code_chunk, $sub_matches); $code_allowed = true; foreach ($sub_matches[1] as $method_name) { if (!in_array($method_name, $this->allowed_methods)) { $code_allowed = false; break; } } if (!$code_allowed) { $template_code = str_replace($matches[0][$index], '', $template_code); } } return $template_code; } public function render($template_code, $params) { extract($params); ob_start(); eval('?>'.$this->secure_code($template_code).'<?php '); $result = ob_get_contents(); ob_end_clean(); return $result; } } Example usage: $template_code = '<?= $title ?><? foreach ($photos as $photo): ?><img src="<?= $photo ?>"><? endforeach ?>'; $params = array('title' => 'My Title', 'photos' => array('img1.jpg', 'img2.jpg')); $template = new Template; echo $template->render($template_code, $params); The idea here is that I'd store the templates (PHP code) in the database, and then run it through the class which uses regular expressions to only allow permitted methods (if, for, etc.). Anyone see an obvious way to exploit this and run arbitrary PHP? If so, I'll probably go the more standard route of a templating language such as Smarty...

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• Linq to Entities custom ordering via position mapping table

  - by Bigfellahull

  Hi, I have a news table and I would like to implement custom ordering. I have done this before via a positional mapping table which has newsIds and a position. I then LEFT OUTER JOIN the position table ON news.newsId = position.itemId with a select case statement CASE WHEN [position] IS NULL THEN 9999 ELSE [position] END and order by position asc, articleDate desc. Now I am trying to do the same with Linq to Entities. I have set up my tables with a PK, FK relationship so that my News object has an Entity Collection of positions. Now comes the bit I can't work out. How to implement the LEFT OUTER JOIN. I have so far: var query = SelectMany (n => n.Positions, (n, s) => new { n, s }) .OrderBy(x => x.s.position) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); This kinda works. However this uses a INNER JOIN so not what I am after. I had another idea: ret = ret.OrderBy(n => n.ShufflePositions.Select(s => s.position)); However I get the error DbSortClause expressions must have a type that is order comparable. I also tried ret = ret.GroupJoin(tse.ShufflePositions, n => n.id, s => s.itemId, (n, s) => new { n, s }) .OrderBy(x => x.s.Select(z => z.position)) .ThenByDescending(x => x.n.articleDate) .Select(x => x.n); but I get the same error! If anyone can help me out, it would be much appreciated!

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• Performance difference in for loop condition?

  - by CSharperWithJava

  Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm not a beginner to coding by any means, but I've never bothered with the comma operator. Are there performance/behavior differences or is it purely aesthetic? One last note, I know there are bigger performance fish to fry than a conditional operator, but I'm just curious. Indulge me. Edit Thanks for your answers. It turns out the code that prompted this question had misused the comma operator in the way I've described. I wondered what the difference was and why it wasn't a && operator, but it was just written incorrectly. I didn't think anything was wrong with it because it worked just fine. Thanks for straightening me out.

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• Using ADO.NET Entities LINQ Provider to model complex SQL Queries?

  - by Ivan Zlatanov

  What I find really powerful in ADO.NET Entities or LINQ to SQL, is the ability to model complex queries. I really don't need the mappings that Entities or LINQ to SQL are doing for me - I just need the ability to model complex expressions that can be translated into T-SQL. My question is - am I abusing too much? Can I use the Entity Framework for modeling queries and just that? Should I? I know I can write my own custom LINQ to SQL provider, but that is just not possible to handle in the time spans I have. What is the best approach to model complex T-SQL queries? How do you handle conditional group byes, orders, joins, unions etc in the OOP world? Using StringBuilders for this kind of job feels too ugly and harder to maintain given the possibilities we have with Expression Trees. When I use StringBuilder to model a complex SQL Query I feel kind of guilty! I feel the same way as when I have to hard code any number into my code that is different than 0 or 1. Feeling that makes you ask yourself if there is a better and cleaner way of doing it... I must mention that I am using C# 4.0, but I am not specifically looking for an answer in this language, but rather in the domain of CLR 4.

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• Pass Linq Expression to a function

  - by Kushan Hasithe Fernando

  I want to pass a property list of a class to a function. with in the function based on property list I'm going to generate a query. As exactly same functionality in Linq Select method. Here I'm gonna implement this for Ingress Database. As an example, in front end I wanna run a select as this, My Entity Class is like this public class Customer { [System.Data.Linq.Mapping.ColumnAttribute(Name="Id",IsPrimaryKey=true)] public string Id { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Name")] public string Name { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Address")] public string Address { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Email")] public string Email { get; set; } [System.Data.Linq.Mapping.ColumnAttribute(Name = "Mobile")] public string Mobile { get; set; } } I wanna call a Select function like this, var result = dataAccessService.Select<Customer>(C=>C.Name,C.Address); then,using result I can get the Name and Address properties' values. I think my Select function should looks like this, ( *I think this should done using Linq Expression. But im not sure what are the input parameter and return type. * ) Class DataAccessService { // I'm not sure about this return type and input types, generic types. public TResult Select<TSource,TResult>(Expression<Func<TSource,TResult>> selector) { // Here using the property list, // I can get the ColumnAttribute name value and I can generate a select query. } } This is a attempt to create a functionality like in Linq. But im not an expert in Linq Expressions. There is a project call DbLinq from MIT, but its a big project and still i couldn't grab anything helpful from that. Can someone please help me to start this, or can someone link me some useful resources to read about this.

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• Get controls ClientID/UniqueID between DetailsView and UpdatePanel

  - by robertpnl

  Hi guys, I like to know how to get the ClientID/UniqueID of a control inside a Detailsview controls EditItemTemplate element and when DetailsViews changing to Edit mode and DetailsView is inside a AJAX UpdatePanel. Without UpdatePanel, during PostBack I can get the ClientID's control, but now with an UpdatePanel. <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional"> <ContentTemplate> <asp:DetailsView ID="DetailsView1" runat="server" DataSourceID="SqlDataSource1" AllowPaging="true" AutoGenerateEditButton="true"> <Fields> <asp:TemplateField> <EditItemTemplate> <asp:CheckBox runat="server" ID="chkboxTest" Text="CHECKBOX" /> </EditItemTemplate> </asp:TemplateField> </Fields> </asp:DetailsView> </ContentTemplate> </asp:UpdatePanel> As you see, the EditItemTemplate contains a Checkbox control. So i'm trying to get the ClientID of this checkbox when Detailsview is changing to the Edit mode. I need this value for handling Javascript. Catching the events ChangingMode/ChangedMode doesn't work; chkbox is null: void DetailsView1_ModeChanged(object sender, EventArgs e) { if (DetailsView1.CurrentMode == DetailsViewMode.Edit) var chkbox = DetailsView1.Rows[0].FindControl("chkxboxTest"); // <== is null } Maybe i'm using the wrong event? Someone can give me a tip about this? Thanks.

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• C/C++ Control Structure Limitations?

  - by STingRaySC

  I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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• Java: Help constructing a fillTextFields() method

  - by Holly

  I have a Java project where I am to connect to a database and create buttons (next, new, save, delete, previous) to navigate through the database content where there are appropriate text fields and labels for the specific information. I'll use the code below as an example (each button is set up very similar)... I have it as follows: JButton jbtnNext = new JButton("Next ->"); jbtnNext.addActionListener(this); if (e.getSource() == jbtnNext) jbtnNext_Click(); private void jbtnNext_Click() { JOptionPane.showMessageDialog(null, "Next" ,"Button Pressed", JOptionPane.INFORMATION_MESSAGE); try { if (rset.next()) { fillTextFields(true); }else{ //Display result in a dialog box JOptionPane.showMessageDialog(null, "Not found"); } } catch (SQLException ex) { ex.printStackTrace(); } } The professor gave the following outline of logic to construct the fillTextFields() method: Construct the method to provide reusable code that would fill the JTextFields on the GUI with appropriate values from current record from the database (when "Previous or "Next" buttons are pressed) or blank values (when the new Button is pressed). To determine when the current record was to provide values (next and previous) or the value would be blank (new button) pass a boolean argument into the method. If data from the current record was to be used as fill values, pass true for both previous and next button code after moving the record pointer. If the new button was pressed and want to fill with blank values, pass false to the method. Inside the method, use a conditional expression to evaluate the boolean variable. If true, The appropriate get----() resultset method is used to fill the JTextFields. If false, fill them with "". The .setText() method of the JTextField is used to fill each JTextField. Make sure the fillTextFields method throws the appropriate exception. I understand and have the previous and next button methods passing true, while the new button method is passing false, but I don't quite understand how to set up the fillTextFields() method correctly or how to "throw the appropriate exception"... Any help would really be appreciated, thank you!

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• Spring Security 3.0- Customise basic http Authentication Dialog

  - by gav

  Rather than reading; A user name and password are being requested by http://localhost:8080. The site says: "Spring Security Application" I want to change the prompt, or at least change what the "site says". Does anyone know how to do this via resources.xml? In my Grails App Spring configuration, my current version is as follows; <?xml version="1.0" encoding="UTF-8"?> <beans:beans xmlns="http://www.springframework.org/schema/security" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.xsd"> <http auto-config="true" use-expressions="true"> <http-basic/> <intercept-url pattern="/**" access="isAuthenticated()" /> </http> <authentication-manager alias="authenticationManager"> <authentication-provider> <user-service> <user name="admin" password="admin" authorities="ROLE_ADMIN"/> </user-service> </authentication-provider> </authentication-manager> </beans:beans>

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• How to access valuestack objects within struts iterator?

  - by Monika Michael

  I have following code - <s:iterator value="reviews"> <img src="<s:property value="#request.restaurant.portalImage.url" />" /> <s:property value="user.firstName" /> <s:property value="user.lastName" /> <s:property value="rating" /> <s:property value="review" /> </s:iterator> reviews is a list of review objects which contain details of a review, such as rating and name of user. My problem is that i'm not able to access any of the objects present on the valuestack within the loop. Outside the loop <s:property value="#request.restaurant.portalImage.url" /> works correctly. But within the loop it prints null. AFAIK an iterator pushes it's collection on the valuestack so that all ognl expressions resolve against it. But I've used # which means I'm explicitly specifying the root object for resolution. Why is it still not working?

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• Representing element as boolean with JAXB?

  - by Marcus

  We have this XML: <Summary> <ValueA>xxx</ValueA> <ValueB/> </Summary> <ValueB/> will never have any attributes or inner elements. It's a boolean type element - it exists (true) or it doesn't (false). JAXB generated a Summary class with a String valueA member, which is good. But for ValueB, JAXB generated a ValueB inner class and a corresponding member: @XmlElement(name = "ValueB") protected Summary.ValueB valueB; But what I'd like is a boolean member and no inner class: @XmlElement(name = "ValueB") protected boolean valueB; How can you do this? I'm not looking to regenerate the classes, I'd like to just make the code change manually. Update: In line with the accepted answer, we created a new method returning the boolean value conditional on whether valueB == null. As we are using Hibernate, we annotated valueB with @Transient and annotated the boolean getter with Hibernate's @Column annotation.

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• JS/CSS include section replacement, Debug vs Release

  - by Bayard Randel

  I'd be interested to hear how people handle conditional markup, specifically in their masterpages between release and debug builds. The particular scenario this is applicable to is handling concatenated js and css files. I'm currently using the .Net port of YUI compress to produce a single site.css and site.js from a large collection of separate files. One thought that occurred to me was to place the js and css include section in a user control or collection of panels and conditionally display the <link> and <script> markup based on the Debug or Release state of the assembly. Something along the lines of: #if DEBUG pnlDebugIncludes.visible = true #else pnlReleaseIncludes.visible = true #endif The panel is really not very nice semantically - wrapping <script> tags in a <div> is a bit gross; there must be a better approach. I would also think that a block level element like a <div> within <head> would be invalid html. Another idea was this could possibly be handled using web.config section replacements, but I'm not sure how I would go about doing that.

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• Deal with undefined values in code or in the template?

  - by David

  I'm writing a web application (in Python, not that it matters). One of the features is that people can leave comments on things. I have a class for comments, basically like so: class Comment: user = ... # other stuff where user is an instance of another class, class User: name = ... # other stuff And of course in my template, I have <div>${comment.user.name}</div> Problem: Let's say I allow people to post comments anonymously. In that case comment.user is None (undefined), and of course accessing comment.user.name is going to raise an error. What's the best way to deal with that? I see three possibilities: Use a conditional in the template to test for that case and display something different. This is the most versatile solution, since I can change the way anonymous comments are displayed to, say, "Posted anonymously" (instead of "Posted by ..."), but I've often been told that templates should be mindless display machines and not include logic like that. Also, other people might wind up writing alternate templates for the same application, and I feel like I should be making things as easy as possible for the template writer. Implement an accessor method for the user property of a Comment that returns a dummy user object when the real user is undefined. This dummy object would have user.name = 'Anonymous' or something like that and so the template could access it and print its name with no error. Put an actual record in my database corresponding to a user with user.name = Anonymous (or something like that), and just assign that user to any comment posted when nobody's logged in. I know I've seen some real-world systems that operate this way. (phpBB?) Is there a prevailing wisdom among people who write these sorts of systems about which of these (or some other solution) is the best? Any pitfalls I should watch out for if I go one way vs. another? Whoever gives the best explanation gets the checkmark.

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• Regular expression to match HTML table row ( <tr> ) NOT containing a specific value

  - by user1821136

  I'm using Notepad++ to clean up a long and messy HTML table. I'm trying to use regular expressions even if I'm a total noob. :) I need to remove all the table rows that doesn't contain a specific value (may I call that substring?). After having all the file contents unwrapped, I've been able to use the following regular expression to select, one by one, every table row with all its contents: <tr>.+?</tr> How can I improve the regular expression in order to select and replace only table rows containing, somewhere inside a part of them, that defined substring? I don't know if this does matter but the structure of every table row is the following (I've put there every HTML tag, the dots stand for standard content/values) <tr> <td> ... </td> <td> ... </td> <td> <a sfref="..." href="...">!! SUBSTRING I HAVE TO MATCH HERE !!</a> </td> <td> <img /> </td> <td> ... </td> <td> ... </td> <td> ... </td> <td> ... </td> </tr> Thanks in advance for your help!

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• Displaying same record twice- SQL Reporting Services

  - by RyanW

  Ok, here's the situation: I need to display the same record in two different sections. stupid i know, but here's why. The Report I am building is grouped by one Field, called Day. Each record has date/times, an expected arrival date time, and an expected departure date/time. so, at this point we have something like this: Day..............Arrival Time..................Departure Time 18/5.............18/5 9.00am.........19/5 11.00am The boss only wants to show times that relate to the current day in the arrive/depart coloumns (easy enough with expressions), which ends up like this: Day..............Arrival Time..................Departure Time 18/5..............9.00am.........................- the next thing he wants is to display the departing time in the correct day 'group', but as you can imagine as soon as you move to the next row, well you move to the next row of the table. So the question is: is there anyway to display the same record on multiple coloumns? Have i missed something or have i got an unsolvable problem? NOTE: this is not the only data in my table either. there is (for example) a name coloumn which also needs to be displayed on both days.

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• Type result with Ternary operator in C#

  - by Vaccano

  I am trying to use the ternary operator, but I am getting hung up on the type it thinks the result should be. Below is an example that I have contrived to show the issue I am having: class Program { public static void OutputDateTime(DateTime? datetime) { Console.WriteLine(datetime); } public static bool IsDateTimeHappy(DateTime datetime) { if (DateTime.Compare(datetime, DateTime.Parse("1/1")) == 0) return true; return false; } static void Main(string[] args) { DateTime myDateTime = DateTime.Now; OutputDateTime(IsDateTimeHappy(myDateTime) ? null : myDateTime); Console.ReadLine(); ^ } | } | // This line has the compile issue ---------------+ On the line indicated above, I get the following compile error: Type of conditional expression cannot be determined because there is no implicit conversion between '< null ' and 'System.DateTime' I am confused because the parameter is a nullable type (DateTime?). Why does it need to convert at all? If it is null then use that, if it is a date time then use that. I was under the impression that: condition ? first_expression : second_expression; was the same as: if (condition) first_expression; else second_expression; Clearly this is not the case. What is the reasoning behind this? (NOTE: I know that if I make "myDateTime" a nullable DateTime then it will work. But why does it need it? As I stated earlier this is a contrived example. In my real example "myDateTime" is a data mapped value that cannot be made nullable.)

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• Which technology should I use to transform my latex documents into html documents

  - by Matthias Günther

  Hey, I want to write a little program that transforms my TeX files into HTML. I want to parse the documents and turn the macros (the build-in and of course my own) into HTML pieces. Here are my requirements: predefined rules (e.g. begin{itemize} \item text \end{itemize} = <br> <p>text </p> <br/>) defining own CSS style ability to convert formulars (extract the formulars, load them in an imagecreator and then save the jpg/png) easy to maintain and concise I know there are several technologies out there, but I don't exactly know which is the best for me. Here are the technologies which flow into my mind Ruby (I/O is easy, formular loading via webrat), XML XSLT (I don't think that I need just overhead) perl (there are many libs out there but I'm not quite familiar with it) bash (I worked with sed and was surprised how easy it was to work with regular expressions) latex2html ... (these converters won't work for me and they don't give me freedom in parsing) Any suggestions, hints and comments are welcome. Thanks for your time, folks.

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• What are the lengths/limits C preprocessor as a language creation tool? Where can I learn more about

  - by Weston C

  In his FAQ @ http://www2.research.att.com/~bs/bs_faq.html#bootstrapping, Bjarne Stroustrup says: To build [Cfront, the first C++ compiler], I first used C to write a "C with Classes"-to-C preprocessor. "C with Classes" was a C dialect that became the immediate ancestor to C++... I then wrote the first version of Cfront in "C with Classes". When I read this, it piqued my interest in the C preprocessor. I'd seen its macro capabilities as suitable for simplifying common expressions but hadn't thought about its ability to significantly add to syntax and semantics on the level that I imagine bringing classes to C took. So now I have a couple of questions on my mind: 1) Are there other examples of this approach to bootstrapping a language off of C? 2) Is the source to Stroustrup's original work available anywhere? 3) Where could I learn more about the specifics of utilizing this technique? 4) What are the lengths/limits of that approach? Could one, say, create a set of preprocessor macros that let someone write in something significantly Lisp/Scheme like?

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• Custom server control disappears from page when UpdatePanel updates

  - by Sasha

  Hi all. I created a custom asp.net server control. It works fine on a regular asp.net page and as a DOM object inside of the browser. But I've never used the UpdatePanel before and now I'm trying to make sure that this control works there as well. It doesn't. If I add my control to the page outside of an update panel and click some panel's inside button (trigger), everything works fine. But if I place my control inside of update panel and click that button again, the control "disappears" from the page completely. I still can see my control in javascript debugger and the update, meaning that the object itself is still in DOM. It looks like the panel just "hides" the outer div element of my control for some reason. I tried to call panel's Update() method on button click handler, set panel's UpdateMode to both Conditional and Always. All with the same result. How can I fix that? Thank you!

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• C++ converting back and forth from derived and base classes

  - by user127817

  I was wondering if there is a way in C++ to accomplish the following: I have a base class called ResultBase and two class that are Derived from it, Variable and Expression. I have a few methods that do work on vector<ResultBase> . I want to be able to pass in vectors of Variable and Expression into these methods. I can achieve this by creating a vector<ResultBase> and using static_cast to fill it with the members from my vector of Variable/Expression. However, once the vector has run through the methods, I want to be able to get it back as the vector of Result/Expression. I'll know for sure which one I want back. static_cast won't work here as there isn't a method to reconstruct a Variable/Expression from a ResultBase, and more importantly I wouldn't have the original properties of the Variables/Expressions The methods modify some of the properties of the ResultBase and I need those changes to be reflected in the original vectors. (i.e. ResultBase has a property called IsLive, and one of the methods will modify this property. I want this IsLive value to be reflected in the derived class used to create the ResultBase Whats the easiest way to accomplish this?

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