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  • C typedef struct uncertainty.

    - by Emanuel Ey
    Consider the following typedef struct in C: 21:typedef struct source{ 22: double ds; //ray step 23: double rx,zx; //source coords 24: double rbox1, rbox2; //the box that limits the range of the rays 25: double freqx; //source frequency 26: int64_t nThetas; //number of launching angles 27: double theta1, thetaN; //first and last launching angle 28:}source_t; I get the error: globals.h:21: error: redefinition of 'struct source' globals.h:28: error: conflicting types for 'source_t' globals.h:28: note: previous declaration of 'source_t' was here I've tried using other formats for this definition: struct source{ ... }; typedef struct source source_t; and typedef struct{ ... }source_t; Which both return the same error. Why does this happen? it looks perfectly right to me.

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  • Is there performance to be gained by moving storage allocation local to a member function to its cla

    - by neuviemeporte
    Suppose I have the following C++ class: class Foo { double bar(double sth); }; double Foo::bar(double sth) { double a,b,c,d,e,f a = b = c = d = e = f = 0; /* do stuff with a..f and sth */ } The function bar() will be called millions of times in a loop. Obviously, each time it's called, the variables a..f have to be allocated. Will I gain any performance by making the variables a..f members of the Foo class and just initializing them at the function's point of entry? On the other hand, the values of a..f will be dereferenced through this-, so I'm wondering if it isn't actually a possible performance degradation. Is there any overhead to accessing a value through a pointer? Thanks!

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  • Should I use implicit conversions to enforce preconditions?

    - by Malvolio
    It occurs to me that I could use use implicit conversions to both announce and enforce preconditions. Consider this: object NonNegativeDouble { implicit def int2nnd(d : Double) : NonNegativeDouble = new NonNegativeDouble(d) implicit def nnd2int(d : NonNegativeDouble) : Double = d.v def sqrt(n : NonNegativeDouble) : NonNegativeDouble = scala.math.sqrt(n) } class NonNegativeDouble(val v : Double ) { if (v < 0) { throw new IllegalArgumentException("negative value") } } object Test { def t1 = { val d : Double = NonNegativeDouble.sqrt(3.0); printf("%f\n", d); val n : Double = NonNegativeDouble.sqrt(-3.0); } } Ignore for the moment the actual vacuity of the example: my point is, the subclass NonNegativeDouble expresses the notion that a function only takes a subset of the entire range of the class's values. First is this: A good idea, a bad idea, or an obvious idea everybody else already knows about Second, this would be most useful with basic types, like Int and String. Those classes are final, of course, so is there a good way to not only use the restricted type in functions (that's what the second implicit is for) but also delegate to all methods on the underlying value (short of hand-implementing every delegation)?

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  • How to process <input type="file" name="test1[f]" /> in PHP?

    - by user198729
    var_dump($_FILES) gives the following: array 'test1' => array 'name' => array 'f' => string 'ntuser.dat.LOG' (length=14) 'type' => array 'f' => string 'application/octet-stream' (length=24) 'tmp_name' => array 'f' => string 'D:\wamp\tmp\php223.tmp' (length=22) 'error' => array 'f' => int 0 'size' => array 'f' => int 0 Why is http designed this way?How can I get the file by $_FILES['test1']['f']?

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  • C++ run error: pointer being freed was not allocated

    - by Dale Reves
    I'm learning c++ and am working on a program that keeps giving me a 'pointer being freed was not allocated' error. It's a grocery store program that inputs data from a txt file, then user can enter item# & qty. I've read through similar questions but what's throwing me off is the 'pointer' issue. I would appreciate if someone could take a look and help me out. I'm using Netbeans IDE 7.2 on a Mac. I'll just post the whole piece I have so far. Thx. #include <iostream> #include <fstream> #include <string> #include <vector> using namespace std; class Product { public: // PLU Code int getiPluCode() { return iPluCode; } void setiPluCode( int iTempPluCode) { iPluCode = iTempPluCode; } // Description string getsDescription() { return sDescription; } void setsDescription( string sTempDescription) { sDescription = sTempDescription; } // Price double getdPrice() { return dPrice; } void setdPrice( double dTempPrice) { dPrice = dTempPrice; } // Type..weight or unit int getiType() { return iType; } void setiType( int iTempType) { iType = iTempType; } // Inventory quantity double getdInventory() { return dInventory; } void setdInventory( double dTempInventory) { dInventory = dTempInventory; } private: int iPluCode; string sDescription; double dPrice; int iType; double dInventory; }; int main () { Product paInventory[21]; // Create inventory array Product paPurchase[21]; // Create customer purchase array // Constructor to open inventory input file ifstream InputInventory ("inventory.txt", ios::in); //If ifstream could not open the file if (!InputInventory) { cerr << "File could not be opened" << endl; exit (1); }//end if int x = 0; while (!InputInventory.eof () ) { int iTempPluCode; string sTempDescription; double dTempPrice; int iTempType; double dTempInventory; InputInventory >> iTempPluCode >> sTempDescription >> dTempPrice >> iTempType >> dTempInventory; paInventory[x].setiPluCode(iTempPluCode); paInventory[x].setsDescription(sTempDescription); paInventory[x].setdPrice(dTempPrice); paInventory[x].setiType(iTempType); paInventory[x].setdInventory(dTempInventory); x++; } bool bQuit = false; //CREATE MY TOTAL VARIABLE HERE! int iUserItemCount; do { int iUserPLUCode; double dUserAmount; double dAmountAvailable; int iProductIndex = -1; //CREATE MY SUBTOTAL VARIABLE HERE! while(iProductIndex == -1) { cout<<"Please enter the PLU Code of the product."<< endl; cin>>iUserPLUCode; for(int i = 0; i < 21; i++) { if(iUserPLUCode == paInventory[i].getiPluCode()) { dAmountAvailable = paInventory[i].getdInventory(); iProductIndex = i; } } //PLU code entry validation if(iProductIndex == -1) { cout << "You have entered an invalid PLU Code."; } } cout<<"Enter the quantity to buy.\n"<< "There are "<< dAmountAvailable << "available.\n"; cin>> dUserAmount; while(dUserAmount > dAmountAvailable) { cout<<"That's too many, please try again"; cin>>dUserAmount; } paPurchase[iUserItemCount].setiPluCode(iUserPLUCode);// Array of objects function calls paPurchase[iUserItemCount].setdInventory(dUserAmount); paPurchase[iUserItemCount].setdPrice(paInventory[iProductIndex].getdPrice()); paInventory[iProductIndex].setdInventory( paInventory[iProductIndex].getdInventory() - dUserAmount ); iUserItemCount++; cout <<"Are you done purchasing items? Enter 1 for yes and 0 for no.\n"; cin >> bQuit; //NOTE: Put Amount * quantity for subtotal //NOTE: Put code to update subtotal (total += subtotal) // NOTE: Need to create the output txt file! }while(!bQuit); return 0; }

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  • Extension method return using generics

    - by Steven de Salas
    Is it possible to return a generic type using extension methods? For example, I have the following method: // Convenience method to obtain a field within a row (as a double type) public static double GetDouble(this DataRow row, string field) { if (row != null && row.Table.Columns.Contains(field)) { object value = row[field]; if (value != null && value != DBNull.Value) return Convert.ToDouble(value); } return 0; } This is currently used as follows: double value = row.GetDouble("tangible-equity"); but I would like to use the following code: double value = row.Get<double>("tangible-equity"); Is this possible and if so, what would the method look like?

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  • <function> referenced from; symbol(s) not found.

    - by jfm429
    I have a piece of C code that is used from a C++ function. At the top of my C++ file I have the line: #include "prediction.h" In prediction.h I have this: #ifndef prediction #define prediction #include "structs.h" typedef struct { double estimation; double variance; } response; response runPrediction(int obs, location* positions, double* observations, int targets, location* targetPositions); #endif I also have prediction.c, which has: #include "prediction.h" response runPrediction(int obs, location* positions, double* observations, int targets, location* targetPositions) { // code here } Now, in my C++ file (which as I said includes prediction.h) I call that function, then compile (through Xcode) I get this error: "runPrediction(int, location*, double*, int, location*)", referenced from: mainFrame::respondTo(char*, int)in mainFrame.o ld: symbol(s) not found collect2: ld returned 1 exit status prediction.c is marked for compilation for the current target. I don't have any problems with other .cpp files not being compiled. Any thoughts here?

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  • PostgeSQL: Arrays Data Type with PHP

    - by ArchJ
    I'm working on PostgeSQL with PHP and I know that PosrgeSQL allow columns of a table to be defined as arrays. So let's say I have a table like this: CREATE TABLE sal_emp ( a text ARRAY, b text ARRAY, c text ARRAY, ); These are my arrays: $a = array(aa,bb,cc); $b = array(dd,dd,aa); $c = array(bb,ff,ee); and I want to insert them into respective column each like this: a | b | c -----------+------------+------------ {aa,bb,cc} | {dd,dd,aa} | {bb,ff,ee} Can I insert it this way? $a = implode(',', $a); $b = implode(',', $b); $c = implode(',', $c); $a = array('a' => $a, 'b' => $b, 'c' => $c); pg_insert($dbconn, 'table', $a); Or is there a better way to achieve the same result?

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  • Enums,use in switch case

    - by WPS
    Hi, I have an Enum defined which contains method return type like "String",Float,List,Double etc. I will be using it in switch case statements. For example my enum is public enum MethodType { DOUBLE,LIST,STRING,ARRAYLIST,FLOAT,LONG; } In a property file, I've key value pairs as follows. Test1=String Test2=Double In my code I'm getting the value for the key. I need to use the VALUE in Switch Case to Determine the Type and based on that I've to implement some logic. For example something like this switch(MethodType.DOUBLE){ case DOUBLE: //Dobule logic } Can someone please help me to implement this?

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  • How to split strings at specific intervals to arrays in javascript

    - by t3st
    how to split strings at specific interveals to arrays in javascript for example: split this string into 4 characters (including space and characters) this is an example should be split,numbers(123),space,characters also included to this ------> 1st array is ------> 2nd array an ------> 3rd array exam ------> 4th array ple ------> 5th array shou ------> 6th array ............ etc till..... ..ed ------> last array

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  • Mapping over multiple Seq in Scala

    - by bsdfish
    Suppose I have val foo : Seq[Double] = ... val bar : Seq[Double] = ... and I wish to produce a seq where the baz(i) = foo(i) + bar(i). One way I can think of to do this is val baz : Seq[Double] = (foo.toList zip bar.toList) map ((f: Double, b : Double) => f+b) However, this feels both ugly and inefficient -- I have to convert both seqs to lists (which explodes with lazy lists), create this temporary list of tuples, only to map over it and let it be GCed. Maybe streams solve the lazy problem, but in any case, this feels like unnecessarily ugly. In lisp, the map function would map over multiple sequences. I would write (mapcar (lambda (f b) (+ f b)) foo bar) And no temporary lists would get created anywhere. Is there a map-over-multiple-lists function in Scala, or is zip combined with destructuring really the 'right' way to do this?

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  • javascript splice() indexing problem

    - by markzzz
    hello! i have to add some value into an array. code for example : temp[0]=new Array("0","0"); temp[1]=new Array("0","0"); temp[2]=new Array("0","0"); temp[3]=new Array("0","0"); temp[4]=new Array("0","0"); vt=new Array("1","0"); temp.splice(3, 0, vt); temp.splice(4, 0, vt); temp[3][1]="R"; i aspect this output : 1 - 0,0 2 - 0,0 3 - 0,0 4 - 1,R 5 - 1,0 6 - 0,0 7 - 0,0 but the output is : 1 - 0,0 2 - 0,0 3 - 0,0 4 - 1,R 5 - 1,R 6 - 0,0 7 - 0,0 any idea? i think it's a indexing problem with splice() function! cheers

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  • How can I convert a decimal to a fraction ?

    - by CornyD
    How do I convert a indefinite decimal (i.e. .333333333...) to a string fraction representation (i.e. "1/3"). I am using VBA and the following is the code I used (i get an overflow error at the line "b = a Mod b": Function GetFraction(ByVal Num As Double) As String If Num = 0# Then GetFraction = "None" Else Dim WholeNumber As Integer Dim DecimalNumber As Double Dim Numerator As Double Dim Denomenator As Double Dim a, b, t As Double WholeNumber = Fix(Num) DecimalNumber = Num - Fix(Num) Numerator = DecimalNumber * 10 ^ (Len(CStr(DecimalNumber)) - 2) Denomenator = 10 ^ (Len(CStr(DecimalNumber)) - 2) If Numerator = 0 Then GetFraction = WholeNumber Else a = Numerator b = Denomenator t = 0 While b <> 0 t = b b = a Mod b a = t Wend If WholeNumber = 0 Then GetFraction = CStr(Numerator / a) & "/" & CStr(Denomenator / a) Else GetFraction = CStr(WholeNumber) & " " & CStr(Numerator / a) & "/" & CStr(Denomenator / a) End If End If End If End Function

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  • C# Insert ArrayList in DataRow

    - by Emre Kabaoglu
    I want to insert an arraylist in Datarow. using this code, ArrayList array=new ArrayList(); foreach (string s in array) { valuesdata.Rows.Add(s); } But My datatable must have only one datarow. My code created eight datarows. I tried, valuesdata.Rows.Add(array); But it doesn't work.That should be valuesdata.Rows.Add(array[0],array[1],array[2],array[3]....); How can I solve this problem? Thanks.

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  • Defining multiple VBA objects within one function or sub-routine?

    - by Harokitty
    I have the following VBA code: Option Explicit Private a(2) as Double Private b(2) as Double Public Function Hello(X1 As Double, X2 As Double) As Double a(1) = X1 + X2 a(2) = X1/X2 b(1) = X1 b(2) = X2^2 Hello = a(1)+a(2)+b(1)+b(2) End Function Within the function Hello I have defined a(1),a(2),b(1),b(2). However, I want to make some function or sub-routine that accepts X1 and X2 as arguments and spits out the values for a(1),a(2),b(1),b(2). This is because I use the above definitions for a(1),a(2),b(1),b(2) in about 20 functions in my module and would like to avoid having to do the following in each function that I use thesis in: a(1) = X1 + X2 a(2) = X1/X2 b(1) = X1 b(2) = X2^2

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  • Scala : reference is ambiguous (imported twice)

    - by tk
    I want to use a method as a parameter of another method of the same class. I have a class and objects which are companions: class mM(var elem:Matrix){ //apply a function on a dimension rows (1) or cols (2) def app(func:Iterable[Double]=>Double)(dim : Int) : Matrix = { ... } //utility function def logsumexp(): Double = {...} } object mM{ def apply(elem:Matrix):mM={new mM(elem)} def logsumexp(elem:Iterable[Double]): Double ={ this.apply(elem.asInstanceOf[Matrix]).logsumexp() } } Normally I use logsumexp like this mM(matrix).logsumexp but if want to apply it to the rows I can't use mM(matrix).app(mM.logsumexp)(1), I get the error: error: reference to mM is ambiguous; it is imported twice in the same scope by import mM and import mM What is the most elegant solution ? Should I change logsumexp() to another class ? Thanks,=)

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  • how to pass variable arguments from one function to other in tcl

    - by vaichidrewar
    I want to pass variable arguments obtained in one function to other function but I am not able to do so. Function gets even number of variable arguments and then it has to be converted in array. Below is the example. Procedure abc1 gets two arguments (k k) and not form abc1 procedure these have to be passed to proc abc where list to array conversion it to be done. List to array conversion works in proc1 i.e. abc1 but not in second proc i.e. abc Error obtained is given below proc abc {args} { puts "$args" array set arg $args } proc abc1 {args} { puts "$args" array set arg $args set l2 [array get arg] abc $l2 } abc1 k k abc k k Output: k k {k k} list must have an even number of elements while executing "array set arg $l1" (procedure "abc" line 8) invoked from within "abc $l2" (procedure "abc1" line 5) invoked from within "abc1 k k" (file "vfunction.tcl" line 18)

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  • which design choose? - pros and cons

    - by Guarava Makanili
    Which of these 3 approches would choose and why? // This is the one I would choose class Car { } class FeeCalculator { public double calculateFee(Car car) { return 0; } } // in that case the problem might be when we use ORM framework and we try to invoke save with parameter Car class Car { private FeeCalculator calculator; public double calculateFee() { return calculator.calculateFee(this); } } class FeeCalculator { public double calculateFee(Car car) { return 0; } } // in that case the problem mentioned above is solved, but I don't like this design class Car { public double calculateFee(FeeCalculator calculator) { return calculator.calculateFee(this); } } class FeeCalculator { public double calculateFee(Car car) { return 0; } }

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  • merge three file into one big file

    - by davit-datuashvili
    suppose that we have three array int a[]=new int[]{4,6,8,9,11,12}; int b[]=new int[]{3,5,7,13,14}; int c[]=new int[]{1,2,15,16,17}; and we want to merge it into one big d array where d.length=a.length+b.length+c.length but we have memory problem it means that we must need use only this d array where we should merge these these three array of course we can use merge sort but can we use merge algorithm without sorting method? like two sorted array we can merge in one sorted array what about three or more array?

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  • Cakephp, i18n, SQL Error, Not unique table/alias

    - by ion
    I get the following SQL error: SQL Error: 1066: Not unique table/alias: 'I18n__name' when doing a simple find query. Any ideas on possible situations that may have caused this?? I'm using a bindModel method to retrieve the data is that related? This is my code: $this->Project->bindModel(array( 'hasOne' => array( 'ProjectsCategories', 'FilterCategory' => array( 'className' => 'Category', 'foreignKey' => false, 'conditions' => array('FilterCategory.id = ProjectsCategories.category_id') )))); $prlist = $this->Project->find('all', array( 'fields' => array('DISTINCT slug','name'), 'conditions' => array('FilterCategory.slug !='=>'uncategorised') ))

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  • Javascript Inheritance and Arrays

    - by Inespe
    Hi all! I am trying to define a javascript class with an array property, and its subclass. The problem is that all instances of the subclass somehow "share" the array property: // class Test function Test() { this.array = []; this.number = 0; } Test.prototype.push = function() { this.array.push('hello'); this.number = 100; } // class Test2 : Test function Test2() { } Test2.prototype = new Test(); var a = new Test2(); a.push(); // push 'hello' into a.array var b = new Test2(); alert(b.number); // b.number is 0 - that's OK alert(b.array); // but b.array is containing 'hello' instead of being empty. why? As you can see I don't have this problem with primitive data types... Any suggestions?

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  • How can I assign a DBNull in a better way?

    - by Mike
    Hi, I need to parse value from a datarow and assign it to another datarow.If the input is valid, then I need to parse it to double or else add a dbnull value to the output.I'm doing the following, is there a better way to do it? public double? GetVolume(object data) { string colValue = data == null ? string.Empty : data.ToString(); double volume; if (!Double.TryParse(colValue.ToString(), out volume)) { return null; } return volume; } public void Assign(DataRow theRowInput,DataRow theRowOutput) { double? volume = GetVolume(theRowInput[0]); if(volumne.HasValue) theRowOutput[0] = volume.value; else theRowOutput[0] = DbNull.Value; return theRowOutput; } Thanks, -M

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  • php and SQL_CALC_FOUND_ROWS

    - by Lizard
    I am trying to add the SQL_CALC_FOUND_ROWS into a query (Please note this isn't for pagination) please note I am trying to add this to a cakePHP query the code I currently have is below: return $this->find('all', array( 'conditions' => $conditions, 'fields'=>array('SQL_CALC_FOUND_ROWS','Category.*','COUNT(`Entity`.`id`) as `entity_count`'), 'joins' => array('LEFT JOIN `entities` AS Entity ON `Entity`.`category_id` = `Category`.`id`'), 'group' => '`Category`.`id`', 'order' => $sort, 'limit'=>$params['limit'], 'offset'=>$params['start'], 'contain' => array('Domain' => array('fields' => array('title'))) )); Note the 'fields'=>array('SQL_CALC_FOUND_ROWS',' this obviously doesn't work as It tries to apply the SQL_CALC_FOUND_ROWS to the table e.g. SELECTCategory.SQL_CALC_FOUND_ROWS, Is there anyway of doing this? Any help would be greatly appreciated, thanks.

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  • Casting in mixed type calculations in C?

    - by yCalleecharan
    Hi, If I define these variables: double x0, xn, h; int n; and I have this mathematical expression: h = (xn - x0)/n; Is it necessary that I cast n into double prior doing the division for maximum accuracy like in h = (xn - x0)/ (double) n; I wrote a program to check the above but both expressions give the same answers. I understand that C will promote the integer to double type as variables xn and x0 are of type double but strangely enough in a book, the second expression with casting was emphasized. Thanks a lot...

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  • PHP arrays & keys - fetching particular ones

    - by Rohan
    Hi Lets say I have an array with a structure like this: $arr= Array( array( "id"=>"a" "type">"apple"), array( "id"=>"b"), array( "id"=>"c"), array( "id"=>"c" "type"=>"banana") ); now I want to have a foreach loop which fetches all the array elements which have a key in them named "type". Something like foreach(all arrays which have type in them as $item) How would I do that? many thanks.

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