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  • Implicit array casting in C#

    - by Malki
    Hi, I have the following classes with an implicit cast operator defined: class A { ... } class B { private A m_a; public B(A a) { this.m_a = a; } public static implicit operator B(A a) { return new B(a); } } Now, I can implicitly cast A to B. But why can't I implicitly cast A[] to B[] ? static void Main(string[] args) { // compiles A a = new A(); B b = a; // doesn't compile A[] arrA = new A[] {new A(), new A()}; B[] arrB = arrA; } Thanks, Malki.

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  • Quick, Beginner C++ Overloading Question - Getting the compiler to perceive << is defined for a spec

    - by Francisco P.
    Hello everyone. I edited a post of mine so I coul I overloaded << for a class, Score (defined in score.h), in score.cpp. ostream& operator<< (ostream & os, const Score & right) { os << right.getPoints() << " " << right.scoreGetName(); return os; } (getPoints fetches an int attribute, getName a string one) I get this compiling error for a test in main(), contained in main.cpp binary '<<' : no operator found which takes a right-hand operand of type 'Score' (or there is no acceptable conversion) How come the compiler doesn't 'recognize' that overload as valid? (includes are proper) Thanks for your time.

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  • C++: How to make comparison function for char arrays?

    - by Newbie
    Is this possible? i get weird error message when i put char as the type: inline bool operator==(const char *str1, const char *str2){ // ... } Error message: error C2803: 'operator ==' must have at least one formal parameter of class type ... which i dont understand at all. I was thinking if i could directly compare stuff like: const char *str1 = "something"; const char *str2 = "something else"; const char str3[] = "lol"; // not sure if this is same as above and then compare: if(str1 == str2){ // ... } etc. But i also want it to work with: char *str = new char[100]; and: char *str = (char *)malloc(100); I am assuming every char array i use this way would end in NULL character, so the checking should be possible, but i understand it can be unsafe etc. I just want to know if this is possible to do, and how.

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  • question regarding "this" pointer in c++

    - by sil3nt
    hello there, i have been given class with int variables x and y in private, and an operator overload function, class Bag{ private: int x; int y; public: Bag(); ~Bag(); //....... //.....etc }; Bag operator+ (Bag new) const{ Bag result(*this); //what does this mean? result.x += new.x; result.y += new.y; } What is the effect of having "Bag result(*this);" there?.

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  • Excel Interop: Range.FormatConditions.Add throws MissingMethodException

    - by Zach Johnson
    I am writing an application which uses the Microsoft.Office.Interop.Excel assembly to export/import data from Excel spreadsheets. Everything was going fine (except for 1 based indexing and all those optional parameters!), until I tried to use conditional formatting. When I call Range.FormatConditions.Add I get a MissingMethodException telling me that no such method exists. This happens in both Vista and XP. Here's an example of the code that generates the exception: //1. Add a reference to Microsoft.Office.Interop.Excel (version 11.0.0.0) //2. Compile and run the following code: using Microsoft.Office.Interop.Excel; class Program { static void Main(string[] args) { Application app = new Application(); Workbook workbook = app.Workbooks[1]; Worksheet worksheet = (Worksheet)workbook.Worksheets[1]; Range range = worksheet.get_Range("A1", "A5"); FormatCondition condition = range.FormatConditions.Add( XlFormatConditionType.xlCellValue, XlFormatConditionOperator.xlBetween, 100, 200); } }

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  • CPP extension and multiline literals in Haskell

    - by jetxee
    Is it possible to use CPP extension on Haskell code which contains multiline string literals? Are there other conditional compilation techniques for Haskell? For example, let's take this code: -- If the next line is uncommented, the program does not compile. -- {-# LANGUAGE CPP #-} msg = "Hello\ \ Wor\ \ld!" main = putStrLn msg If I uncomment {-# LANGUAGE CPP #-}, then GHC refutes this code with a lexical error: [1 of 1] Compiling Main ( cpp-multiline.hs, cpp-multiline.o ) cpp-multiline.hs:4:17: lexical error in string/character literal at character 'o' Using GHC 6.12.1, cpphs is available. I confirm that using cpphs.compat wrapper and -pgmP cpphs.compat option helps, but I'd like to have a solution which does not depend on custom shell scripts. -pgmP cpphs does not work. P.S. I need to use different code for GHC < 6.12 and GHC = 6.12, is it possible without preprocessor?

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  • [Assembly] jnz after xor?

    - by kotarou3
    After using IDA Pro to disassemble a x86 dll, I found this code (Comments added by me in pusedo-c code. I hope they're correct): test ebx, ebx ; if (ebx == false) jz short loc_6385A34B ; Jump to 0x6385a34b mov eax, [ebx+84h] ; eax = *(ebx+0x84) mov ecx, [esi+84h] ; ecx = *(esi+0x84) mov al, [eax+30h] ; al = *(*(ebx+0x84)+0x30) xor al, [ecx+30h] ; al = al XOR *(*(esi+0x84)+0x30) jnz loc_6385A453 Lets make it simpler for me to understand: mov eax, b3h xor eax, d6h jnz ... How does the conditional jump instruction work after a xor instruction?

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  • How to not run function if its a mobile device?

    - by Deshiknaves
    I have a modal pop up function on my website, but i don't want this to run if the browser is smaller than 480px. I have found that if I put an if statement such as: if (window.innerWidth && window.innerWidth > 480) { run function() } Then it should run only if the browsers innerWidth is 480. However its not working and I think its because I have page scaling on this website. Can any one help me with a conditional statement if page scaling is on? Thanks.

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  • Chained inequality notation in programming languages

    - by Davorin
    Is there a programming language that supports chained notation a < b < c to be used instead of a < b and b < c in conditional statements? Example: if ( 2 < x < 5 ) if ( 2 < x && x < 5 ) First statementlooks better to me, it's easier to understand and the compiler could use transitivity property to warn about mistakes (e.g. 5 < x < 2 would give a warning).

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  • LINQ to Entity, using a SQL LIKE operator

    - by Mario
    I have a LINQ to ENTITY query that pulls from a table, but I need to be able to create a "fuzzy" type search. So I need to add a where clause that searches by lastname IF they add the criteria in the search box (Textbox, CAN be blank --- in which case it pulls EVERYTHING). Here is what I have so far: var query = from mem in context.Member orderby mem.LastName, mem.FirstName select new { FirstName = mem.FirstName, LastName = mem.LastName, }; That will pull everything out of the Member table that is in the Entity object. Then I have an addition to the logic: sLastName = formCollection["FuzzyLastName"].ToString(); if (!String.IsNullOrEmpty(sLastName)) query = query.Where(ln => ln.LastName.Contains(sLastName)); The problem is when the search button is pressed, nothing is returned (0 results). I have run the query against the SQL Server that I expect to happen here and it returns 6 results. This is the query I expect: SELECT mem.LastName, mem.FirstName FROM Members mem WHERE mem.LastName = 'xxx' (when xxx is entered into the textbox) Anyone see anything wrong with this?

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  • Javascript || or operator with a undefinded variable

    - by bryan sammon
    I have been doing some reading lately one article I read was from Opera. http://dev.opera.com/articles/view/javascript-best-practices/ In that article they write this: Another common situation in JavaScript is providing a preset value for a variable if it is not defined, like so: if(v){ var x = v; } else { var x = 10; } The shortcut notation for this is the double pipe character: var x = v || 10; For some reason I cant get this to work for me. Is it really possible to check to see if v is defined, if not x = 10? --Thanks. Bryan

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  • index help for a MySQL query using greater-than operator and ORDER BY

    - by Jaymon
    I have a table with at least a couple million rows and a schema of all integers that looks roughly like this: start stop first_user_id second_user_id The rows get pulled using the following queries: SELECT * FROM tbl_name WHERE stop >= M AND first_user_id=N AND second_user_id=N ORDER BY start ASC SELECT * FROM tbl_name WHERE stop >= M AND first_user_id=N ORDER BY start ASC I cannot figure out the best indexes to speed up these queries. The problem seems to be the ORDER BY because when I take that out the queries are fast. I've tried all different types of indexes using the standard index format: ALTER TABLE tbl_name ADD INDEX index_name (index_col_1,index_col_2,...) And none of them seem to speed up the queries. Does anyone have any idea what index would work? Also, should I be trying a different type of index? I can't guarantee the uniqueness of each row so I've avoided UNIQUE indexes. Any guidance/help would be appreciated. Thanks!

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  • DataTable.Select Behaves Strangely Using ISNULL Operator on NULL DateTime Column

    - by Paul Williams
    I have a DataTable with a DateTime column, "DateCol", that can be DBNull. The DataTable has one row in it with a NULL value in this column. I am trying to query rows that have either DBNull value in this column or a date that is greater than today's date. Today's date is 5/11/2010. I built a query to select the rows I want, but it did not work as expected. The query was: string query = "ISNULL(DateCol, '" + DateTime.MaxValue + "'") > "' + DateTime.Today "'" This results in the following query: "ISNULL(DateCol, '12/31/9999 11:59:59 PM') > '5/11/2010'" When I run this query, I get no results. It took me a while to figure out why. What follows is my investigation in the Visual Studio immediate window: > dt.Rows.Count 1 > dt.Rows[0]["DateCol"] {} > dt.Rows[0]["DateCol"] == DBNull.Value true > dt.Select("ISNULL(DateCol,'12/31/9999 11:59:59 PM') > '5/11/2010'").Length 0 <-- I expected 1 Trial and error showed a difference in the date checks at the following boundary: > dt.Select("ISNULL(DateCol, '12/31/9999 11:59:59 PM') > '2/1/2000'").Length 0 > dt.Select("ISNULL(DateCol, '12/31/9999 11:59:59 PM') > '1/31/2000'").Length 1 <-- this was the expected answer The query works fine if I wrap the DateTime field in # instead of quotes. > dt.Select("ISNULL(DateCol, #12/31/9999#) > #5/11/2010#").Length 1 My machine's regional settings is currently set to EN-US, and the short date format is M/d/yyyy. Why did the original query return the wrong results? Why would it work fine if the date was compared against 1/31/2000 but not against 2/1/2000?

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  • Regex not operator

    - by Erik Goens
    I need to use a regex to pull a value out a url domain that will exclude everything but the host (ex: wordpress) and domain type (ex .com). The urls are dynamic and contain 2-3 values for each result (www.example.com or example.org). I am trying to use this expression, but I am only getting back the first letter of every item I am attempting to exclude: Expresssion (?!wordpress|com|www)(\w+|\d+) String example.wordpress.com Results example ordpress om Desired Result example Any assistance would be greatly appreciated

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  • Cocoa @sum array operator too slow - alternatives?

    - by icodestuff
    I've got a text field value bound to a key path that uses @sum. When the array controller is filtered, the text field updates properly, but extremely slowly, lagging the UI or outright beachballing after every key press (less so as the number of items in arrangedObjects decreases). There is no lag if I don't use @sum; I've narrowed it down to this. Is there a faster way to do the same thing?

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  • Microsoft SQL 2005 - using the modulo operator

    - by cc0
    So I have a silly problem, I have not used much MSSQL before, or any SQL for that matter. I basically have a minor mathematical problem that I need solved, and I thought modulo would be good. I have a number of dates in the database, but I need them be rounded off to the closest [dynamic integer] (could be anything from 0 to 5000000) which will be input as a parameter each time this query is called. So I thought I'd use modulo to find the remainder, then subtract that remainder from the date. If there is a better way, or an integrated function, please let me know! What would be the syntax for that? I've tried a lot of things, but I keep getting error messages like integers/floats/decimals can't be used with the modulo operators. I tried casting to all kinds of numeric datatypes. Any help would be appreciated.

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  • Javascript comma operator

    - by Claudiu
    When combining assignment with comma (something that you shouldn't do, probably), how does javascript determine which value is assigned? Consider these two snippets: function nl(x) { document.write(x + "<br>"); } var i = 0; nl(i+=1, i+=1, i+=1, i+=1); nl(i); And: function nl(x) { document.write(x + "<br>"); } var i = 0; nl((i+=1, i+=1, i+=1, i+=1)); nl(i); The first outputs 1 4 while the second outputs 4 4 What are the parentheses doing here?

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  • PHP Scope Resolution Operator Question

    - by anthony
    I'm having trouble with the MyClass::function(); style of calling methods and can't figure out why. Here's an example (I'm using Kohana framework btw): class Test_Core { public $var1 = "lots of testing"; public function output() { $print_out = $this->var1; echo $print_out; } } I try to use the following to call it, but it returns $var1 as undefined: Test::output() However, this works fine: $test = new Test(); $test->output(); I generally use this style of calling objects as opposed to the "new Class" style, but I can't figure out why it doesn't want to work.

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  • Microsoft SQL Server 2005 - using the modulo operator

    - by cc0
    So I have a silly problem, I have not used much SQL Server before, or any SQL for that matter. I basically have a minor mathematical problem that I need solved, and I thought modulo would be good. I have a number of dates in the database, but I need them be rounded off to the closest [dynamic integer] (could be anything from 0 to 5000000) which will be input as a parameter each time this query is called. So I thought I'd use modulo to find the remainder, then subtract that remainder from the date. If there is a better way, or an integrated function, please let me know! What would be the syntax for that? I've tried a lot of things, but I keep getting error messages like integers/floats/decimals can't be used with the modulo operators. I tried casting to all kinds of numeric datatypes. Any help would be appreciated.

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  • R equivalent of .first or .last sas operator

    - by Giorgio Spedicato
    Does anybody know what is the best R alternative to SAS first. or last. operators? I did find none. SAS has the FIRST. and LAST. automatic variables, which identify the first and last record amongst a group with the same value with a particular variable; so in the following dataset FIRST.model and LAST.model are defined: Model,SaleID,First.Model,Last.Model Explorer,1,1,0 Explorer,2,0,0 Explorer,3,0,0 Explorer,4,0,1 Civic,5,1,0 Civic,6,0,0 Civic,7,0,1

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  • How to use ternary operator instead of if-else in PHP

    - by Mac Taylor
    hey guys i need to shorten or better to say ., harden my codes this is my original code : if ($type = "recent") { $OrderType = "sid DESC"; }elseif ($type = "pop"){ $OrderType = "counter DESC"; }else { $OrderType = "RAND()"; } now how can i use markers like this : $OrderType = ($type = "recent") ? "sid DESC" : "counter DESC" ; i tried but i didnt know how to write elseif in operators

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  • Reverse ?? operator

    - by HeavyWave
    Is it possible to do something like this in C#? logger != null ? logger.Log(message) : ; // do nothing if null or logger !?? logger.Log(message); // do only if not null

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  • STL: writing "where" operator for a vector.

    - by Arman
    Hello, I need to find the indexes in the vector based on several boolean predicates. ex: vector<float> v; vector<int> idx; idx=where( bool_func1(v), bool_func2(v), ... ); What is the way to declare **where** function, in order to use the several user defined boolean functions over the vector? thanks Arman.

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