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  • Casting a container of shared_ptr

    - by Jamie Cook
    Hi all, I have a method void foo(list<shared_ptr<Base>>& myList); Which I'm trying to call with a two different types of lists, one of DerivedClass1 and one of DerivedClass2 list<shared_ptr<DerivedClass1>> myList1; foo(myList1); list<shared_ptr<DerivedClass2>> myList2; foo(myList2); However this obviously generates a compiler error error: a reference of type "std::list<boost::shared_ptr<Base>, std::allocator<boost::shared_ptr<Base>>> &" (not const-qualified) cannot be initialized with a value of type "std::list<boost::shared_ptr<DerivedClass1>, std::allocator<boost::shared_ptr<DerivedClass1>>>" Is there any easy way to cast a container of shared_ptr? Of alternate containers that can accomplish this?

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  • PHP String to Float

    - by John
    I am not familiar with PHP at all and had a quick question. I have 2 variables @pricePerUnit and @invoicedUnits. Here's the code that is setting these to values: $InvoicedUnits = ((string) $InvoiceLineItem->InvoicedUnits); $pricePerUnit = ((string) $InvoiceLineItem->PricePerUnit); If I output this, I get the correct values. Lets say 5000 invoiced units and 1.00 for price. Now, I need to show the total amount spent. When I multiply these two together it doesn't work (as expected, these are strings). But I have no clue how to parse/cast/convert variables in PHP. What should I do?

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  • Convert C++Builder AnsiString to std::string via boost::lexical_cast

    - by David Klein
    For a school assignment I have to implement a project in C++ using Borland C++ Builder. As the VCL uses AnsiString for all GUI Components I have to convert all of my std::strings to AnsiString for the sake of displaying. std::string inp = "Hello world!"; AnsiString outp(inp.c_str()); works of course but is a bit tedious to write and code duplication I want to avoid. As we use Boost in other contexts I decided to provide some helper functions go get boost::lexical_cast to work with AnsiString. Here is my implementation so far: std::istream& operator>>(std::istream& istr, AnsiString& str) { istr.exceptions(std::ios::badbit | std::ios::failbit | std::ios::eofbit); std::string s; std::getline(istr,s); str = AnsiString(s.c_str()); return istr; } In the beginning I got Access Violation after Access Violation but since I added the .exceptions() stuff the picture gets clearer. When the conversion is performed I get the following Exception: ios_base::eofbit set [Runtime Error/std::ios_base::failure] Does anyone have an idea how to fix it and can explain why the error occurs? My C++ experience is very limited. The conversion routine the other way round would be: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); return ostr; } Maybe someone will spot an error here too :) With best regards! Edit: At the moment I'm using the edited version of Jem, it works in the beginning. After a while of using the programm the Borland Codeguard mentions some pointer arithmetic in already freed regions. Any ideas how this could be related? The Codeguard log (I'm using the german version, translations marked with stars): ------------------------------------------ Fehler 00080. 0x104230 (r) (Thread 0x07A4): Zeigerarithmetik in freigegebenem Speicher: 0x0241A238-0x0241A258. **(pointer arithmetic in freed region)** | d:\program files\borland\bds\4.0\include\dinkumware\sstream Zeile 126: | { // not first growth, adjust pointers | _Seekhigh = _Seekhigh - _Mysb::eback() + _Ptr; |> _Mysb::setp(_Mysb::pbase() - _Mysb::eback() + _Ptr, | _Mysb::pptr() - _Mysb::eback() + _Ptr, _Ptr + _Newsize); | if (_Mystate & _Noread) Aufrufhierarchie: **(stack-trace)** 0x00411731(=FOSChampion.exe:0x01:010731) d:\program files\borland\bds\4.0\include\dinkumware\sstream#126 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 0x004080C9(=FOSChampion.exe:0x01:0070C9) D:\Projekte\Schule\foschamp\lib\boost_1_34_1\boost/lexical_cast.hpp#151 Objekt (0x0241A238) [Größe: 32 Byte] war erstellt mit new **(Object was created with new)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 28: | _Ty _FARQ *_Allocate(_SIZT _Count, _Ty _FARQ *) | { // allocate storage for _Count elements of type _Ty |> return ((_Ty _FARQ *)::operator new(_Count * sizeof (_Ty))); | } | Aufrufhierarchie: **(stack-trace)** 0x0040ED90(=FOSChampion.exe:0x01:00DD90) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#28 0x0040E194(=FOSChampion.exe:0x01:00D194) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#143 0x004115CF(=FOSChampion.exe:0x01:0105CF) d:\program files\borland\bds\4.0\include\dinkumware\sstream#105 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 Objekt (0x0241A238) war Gelöscht mit delete **(Object was deleted with delete)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 138: | void deallocate(pointer _Ptr, size_type) | { // deallocate object at _Ptr, ignore size |> ::operator delete(_Ptr); | } | Aufrufhierarchie: **(stack-trace)** 0x004044C6(=FOSChampion.exe:0x01:0034C6) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#138 0x00411628(=FOSChampion.exe:0x01:010628) d:\program files\borland\bds\4.0\include\dinkumware\sstream#111 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 ------------------------------------------ Ansistringkonverter.h is the file with the posted operators and line 31 is: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); **(31)** return ostr; } Thanks for your help :)

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  • How to use the boost lexical_cast library for just for checking input

    - by Inverse
    I use the boost lexical_cast library for parsing text data into numeric values quite often. In several situations however, I only need to check if values are numeric; I don't actually need or use the conversion. So, I was thinking about writing a simple function to test if a string is a double: template<typename T> bool is_double(const T& s) { try { boost::lexical_cast<double>(s); return true; } catch (...) { return false; } } My question is, are there any optimizing compilers that would drop out the lexical_cast here since I never actually use the value? Is there a better technique to use the lexical_cast library to perform input checking?

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  • Passing row from UIPickerView to integer CoreData attribute

    - by Gordon Fontenot
    I'm missing something here, and feeling like an idiot about it. I'm using a UIPickerView in my app, and I need to assign the row number to a 32-bit integer attribute for a Core Data object. To do this, I am using this method: -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { object.integerValue = row; } This is giving me a warning: warning: passing argument 1 of 'setIntegerValue:' makes pointer from integer without a cast What am I mixing up here? --EDIT 1-- Ok, so I can get rid of the errors by changing the method to do the following: NSNumber *number = [NSNumber numberWithInteger:row]; object.integerValue = rating; However, I still get a value of 0 for object.integerValue if I use NSLog to print it out. object.integerValue has a max value of 5, so I print out number instead, and then I'm getting a number above 62,000,000. Which doesn't seem right to me, since there are 5 rows. If I NSLog the row variable, I get a number between 0 and 5. So why do I end up with a completely different number after casting the number to NSNumber?

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  • What OOP pattern to use when only adding new methods, not data?

    - by Jonathon Reinhart
    Hello eveyone... In my app, I have deal with several different "parameters", which derive from IParameter interface, and also ParamBase abstract base class. I currently have two different parameter types, call them FooParameter and BarParameter, which both derive from ParamBase. Obviously, I can treat them both as IParameters when I need to deal with them generically, or detect their specific type when I need to handle their specific functionality. My question lies in specific FooParameters. I currently have a few specific ones with their own classes which derive from FooParameter, we'll call them FP12, FP13, FP14, etc. These all have certain characteristics, which make me treat them differently in the UI. (Most have names associated with the individual bits, or ranges of bits). Note that these specific, derived FP's have no additional data associated with them, only properties (which refer to the same data in different ways) or methods. Now, I'd like to keep all of these parameters in a Dictionary<String, IParameter> for easy generic access. The problem is, if I want to refer to a specific one with the special GUI functions, I can't write: FP12 fp12 = (FP12)paramList["FP12"] because you can't downcast to a derived type (rightfully so). But in my case, I didn't add any data, so the cast would theoretically work. What type of programming model should I be using instead? Thanks!

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  • JTree TreePath casting problem

    - by newbie123
    I got this casting problem java.lang.String cannot be cast to java.io.File, when I trying to do this TreePath p = new TreePath(new Object[] {"src","file","My Diary" }); This is my jtree file model class FileTreeModel implements TreeModel { private FileNode root; public FileTreeModel(String directory) { root = new FileNode(directory); } public Object getRoot() { return root; } public Object getChild(Object parent, int index) { FileNode parentNode = (FileNode) parent; return new FileNode(parentNode, parentNode.listFiles()[index].getName()); } public int getChildCount(Object parent) { FileNode parentNode = (FileNode) parent; if (parent == null || !parentNode.isDirectory() || parentNode.listFiles() == null) { return 0; } return parentNode.listFiles().length; } public boolean isLeaf(Object node) { return (getChildCount(node) == 0); } public int getIndexOfChild(Object parent, Object child) { FileNode parentNode = (FileNode) parent; FileNode childNode = (FileNode) child; return Arrays.asList(parentNode.list()).indexOf(childNode.getName()); } public void valueForPathChanged(TreePath path, Object newValue) { } public void addTreeModelListener(TreeModelListener l) { } public void removeTreeModelListener(TreeModelListener l) { } } class FileNode extends java.io.File { public FileNode(String directory) { super(directory); } public FileNode(FileNode parent, String child) { super(parent, child); } @Override public String toString() { return getName(); } }

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  • static_cast from Derived* to void* to Base*

    - by Roberto
    I would like to cast a pointer to a member of a derived class to void* and from there to a pointer of the base class, like in the example below: #include <iostream> class Base { public: void function1(){std::cout<<"1"<<std::endl;} virtual void function2()=0; }; class Derived : public Base { public: virtual void function2(){std::cout<<"2"<<std::endl;} }; int main() { Derived d; void ptr* = static_cast<void*>(&d); Base* baseptr=static_cast<Base*>(ptr); baseptr->function1(); baseptr->function2(); } This compiles and gives the desired result (prints 1 and 2 respectively), but is it guaranteed to work? The description of static_cast I found here: http://en.cppreference.com/w/cpp/language/static_cast only mentions conversion to void* and back to a pointer to the same class (point 10).

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  • If-elseif-else Logic Question

    - by Changeling
    I have a set of three values, call them x, y, and z. If value A happens to match only one in the set x, y, and z, then that means we have a proper match and we stop searching for a match, even if it is at y. It can match any one in that set. These values x, y, and z are non-constant so I cannot use a switch-case statement. How do I do this with an if-elseif-else statements without having to use GOTO. I am using C++ (no boost or any of that other fancy stuff). Now, I am trying to do this in code and it is racking my brain this morning (not enough coffee?)

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  • Correct usage(s) of const_cast<>

    - by ereOn
    Hi, As a common rule, it is very often considered a bad practice to use const_cast<>() in C++ code as it reveals (most of the time) a flaw in the design. While I totally agree with this, I however wonder what are the cases were using const_cast<>() is ok and the only solution. Could you guys please give me some examples you know/you encountered ? Thank you very much.

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  • GLSL: How Do I cast a float into an int?

    - by dugla
    In a GLSL fragment shader I am trying to cast a float into an int. The compiler has other ideas. It complains thusly: ERROR: 0:60: '=' : cannot convert from 'mediump float' to 'highp int' I am trying to do this: mediump float indexf = floor(2.0 * mixer); highp int index = indexf; I (vainly) tried to raise the precision of the int above the float to appease the GL Gods but no joy. Could someone please school me here? Thanks, Doug

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  • Why this function overloading is not working?

    - by Jack
    class CConfFile { public: CConfFile(const std::string &FileName); ~CConfFile(); ... std::string GetString(const std::string &Section, const std::string &Key); void GetString(const std::string &Section, const std::string &Key, char *Buffer, unsigned int BufferSize); ... } string CConfFile::GetString(const string &Section, const string &Key) { return GetKeyValue(Section, Key); } void GetString(const string &Section, const string &Key, char *Buffer, unsigned int BufferSize) { string Str = GetString(Section, Key); // *** ERROR *** strncpy(Buffer, Str.c_str(), Str.size()); } Why do I get an error too few arguments to function ‘void GetString(const std::string&, const std::string&, char*, unsigned int)' at the second function ? Thanks

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  • Round time to 5 minute nearest SQL Server

    - by Drako
    i don't know if it can be usefull to somebody but I went crazy looking for a solution and ended up doing it myself. Here is a function that (according to a date passed as parameter), returns the same date and approximate time to the nearest multiple of 5. It is a slow query, so if anyone has a better solution, it is welcome. A greeting. CREATE FUNCTION [dbo].[RoundTime] (@Time DATETIME) RETURNS DATETIME AS BEGIN DECLARE @min nvarchar(50) DECLARE @val int DECLARE @hour int DECLARE @temp int DECLARE @day datetime DECLARE @date datetime SET @date = CONVERT(DATETIME, @Time, 120) SET @day = (select DATEADD(dd, 0, DATEDIFF(dd, 0, @date))) SET @hour = (select datepart(hour,@date)) SET @min = (select datepart(minute,@date)) IF LEN(@min) > 1 BEGIN SET @val = CAST(substring(@min, 2, 1) as int) END else BEGIN SET @val = CAST(substring(@min, 1, 1) as int) END IF @val <= 2 BEGIN SET @val = CAST(CAST(@min as int) - @val as int) END else BEGIN IF (@val <> 5) BEGIN SET @temp = 5 - CAST(@min%5 as int) SET @val = CAST(CAST(@min as int) + @temp as int) END IF (@val = 60) BEGIN SET @val = 0 SET @hour = @hour + 1 END IF (@hour = 24) BEGIN SET @day = DATEADD(day,1,@day) SET @hour = 0 SET @min = 0 END END RETURN CONVERT(datetime, CAST(DATEPART(YYYY, @day) as nvarchar) + '-' + CAST(DATEPART(MM, @day) as nvarchar) + '-' + CAST(DATEPART(dd, @day) as nvarchar) + ' ' + CAST(@hour as nvarchar) + ':' + CAST(@val as nvarchar), 120) END

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  • libstdc++ - compiling failing because of tr1/regex

    - by Radek Šimko
    I have these packages installed on my OpenSUSE 11.3: i | libstdc++45 | Standard shared library for C++ | package i | libstdc++45-devel | Contains files and libraries for development | package But when i'm trying to compile this C++ code: #include <stdio.h> #include <tr1/regex> using namespace std; int main() { int test[2]; const tr1::regex pattern(".*"); test[0] = 1; if (tr1::regex_match("anything", pattern) == false) { printf("Pattern does not match.\n"); } return 0; } using g++ -pedantic -g -O1 -o ./main.o ./main.cpp It outputs this errors: ./main.cpp: In function ‘int main()’: ./main.cpp:13:43: error: ‘printf’ was not declared in this scope radek@mypc:~> nano main.cpp radek@mypc:~> g++ -pedantic -g -O1 -o ./main.o ./main.cpp /tmp/cc0g3GUE.o: In function `basic_regex': /usr/include/c++/4.5/tr1_impl/regex:771: undefined reference to `std::tr1::basic_regex<char, std::tr1::regex_traits<char> >::_M_compile()' /tmp/cc0g3GUE.o: In function `bool std::tr1::regex_match<char const*, char, std::tr1::regex_traits<char> >(char const*, char const*, std::tr1::basic_regex<char, std::tr1::regex_traits<char> > const&, std::bitset<11u>)': /usr/include/c++/4.5/tr1_impl/regex:2144: undefined reference to `bool std::tr1::regex_match<char const*, std::allocator<std::tr1::sub_match<char const*> >, char, std::tr1::regex_traits<char> >(char const*, char const*, std::tr1::match_results<char const*, std::allocator<std::tr1::sub_match<char const*> > >&, std::tr1::basic_regex<char, std::tr1::regex_traits<char> > const&, std::bitset<11u>)' collect2: ld returned 1 exit status What packages should i (un)install to make the code work on my PC?

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  • The internal storage of a DATETIME value

    - by Peter Larsson
    SELECT  [Now],         BinaryFormat,         SUBSTRING(BinaryFormat, 1, 4) AS DayPart,         SUBSTRING(BinaryFormat, 5, 4) AS TimePart,         CAST(SUBSTRING(BinaryFormat, 1, 4) AS INT) AS [Days],         DATEADD(DAY, CAST(SUBSTRING(BinaryFormat, 1, 4) AS INT), 0) AS [Today],         CAST(SUBSTRING(BinaryFormat, 5, 4) AS INT) AS [Ticks],         DATEADD(MILLISECOND, 1000.E / 300.E * CAST(SUBSTRING(BinaryFormat, 5, 4) AS INT), 0) AS Peso FROM    (             SELECT  GETDATE() AS [Now],                     CAST(GETDATE() AS BINARY(8)) AS BinaryFormat         ) AS d

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  • Optimize MySQL query (ngrams, COUNT(), GROUP BY, ORDER BY)

    - by Gerardo
    I have a database with thousands of companies and their locations. I have implemented n-grams to optimize search. I am making one query to retrieve all the companies that match with the search query and another one to get a list with their locations and the number of companies in each location. The query I am trying to optimize is the latter. Maybe the problem is this: Every company ('anunciante') has a field ('estado') to make logical deletes. So, if 'estado' equals 1, the company should be retrieved. When I run the EXPLAIN command, it shows that it goes through almost 40k rows, when the actual result (the reality matching companies) are 80. How can I optimize this? This is my query (XXX represent the n-grams for the search query): SELECT provincias.provincia AS provincia, provincias.id, COUNT(*) AS cantidad FROM anunciantes JOIN anunciante_invertido AS a_i0 ON anunciantes.id = a_i0.id_anunciante JOIN indice_invertido AS indice0 ON a_i0.id_invertido = indice0.id LEFT OUTER JOIN domicilios ON anunciantes.id = domicilios.id_anunciante LEFT OUTER JOIN localidades ON domicilios.id_localidad = localidades.id LEFT OUTER JOIN provincias ON provincias.id = localidades.id_provincia WHERE anunciantes.estado = 1 AND indice0.id IN (SELECT invertido_ngrama.id_palabra FROM invertido_ngrama JOIN ngrama ON ngrama.id = invertido_ngrama.id_ngrama WHERE ngrama.ngrama = 'XXX') AND indice0.id IN (SELECT invertido_ngrama.id_palabra FROM invertido_ngrama JOIN ngrama ON ngrama.id = invertido_ngrama.id_ngrama WHERE ngrama.ngrama = 'XXX') AND indice0.id IN (SELECT invertido_ngrama.id_palabra FROM invertido_ngrama JOIN ngrama ON ngrama.id = invertido_ngrama.id_ngrama WHERE ngrama.ngrama = 'XXX') AND indice0.id IN (SELECT invertido_ngrama.id_palabra FROM invertido_ngrama JOIN ngrama ON ngrama.id = invertido_ngrama.id_ngrama WHERE ngrama.ngrama = 'XXX') AND indice0.id IN (SELECT invertido_ngrama.id_palabra FROM invertido_ngrama JOIN ngrama ON ngrama.id = invertido_ngrama.id_ngrama WHERE ngrama.ngrama = 'XXX') GROUP BY provincias.id ORDER BY cantidad DESC And this is the query explained (hope it can be read in this format): id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY anunciantes ref PRIMARY,estado estado 1 const 36669 Using index; Using temporary; Using filesort 1 PRIMARY domicilios ref id_anunciante id_anunciante 4 db84771_viaempresas.anunciantes.id 1 1 PRIMARY localidades eq_ref PRIMARY PRIMARY 4 db84771_viaempresas.domicilios.id_localidad 1 1 PRIMARY provincias eq_ref PRIMARY PRIMARY 4 db84771_viaempresas.localidades.id_provincia 1 1 PRIMARY a_i0 ref PRIMARY,id_anunciante,id_invertido PRIMARY 4 db84771_viaempresas.anunciantes.id 1 Using where; Using index 1 PRIMARY indice0 eq_ref PRIMARY PRIMARY 4 db84771_viaempresas.a_i0.id_invertido 1 Using index 6 DEPENDENT SUBQUERY ngrama const PRIMARY,ngrama ngrama 5 const 1 Using index 6 DEPENDENT SUBQUERY invertido_ngrama eq_ref PRIMARY,id_palabra,id_ngrama PRIMARY 8 func,const 1 Using index 5 DEPENDENT SUBQUERY ngrama const PRIMARY,ngrama ngrama 5 const 1 Using index 5 DEPENDENT SUBQUERY invertido_ngrama eq_ref PRIMARY,id_palabra,id_ngrama PRIMARY 8 func,const 1 Using index 4 DEPENDENT SUBQUERY ngrama const PRIMARY,ngrama ngrama 5 const 1 Using index 4 DEPENDENT SUBQUERY invertido_ngrama eq_ref PRIMARY,id_palabra,id_ngrama PRIMARY 8 func,const 1 Using index 3 DEPENDENT SUBQUERY ngrama const PRIMARY,ngrama ngrama 5 const 1 Using index 3 DEPENDENT SUBQUERY invertido_ngrama eq_ref PRIMARY,id_palabra,id_ngrama PRIMARY 8 func,const 1 Using index 2 DEPENDENT SUBQUERY ngrama const PRIMARY,ngrama ngrama 5 const 1 Using index 2 DEPENDENT SUBQUERY invertido_ngrama eq_ref PRIMARY,id_palabra,id_ngrama PRIMARY 8 func,const 1 Using index

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  • how to solve the errors of this program

    - by hussein abdullah
    include using std::cout; using std::cin; using std::endl; include void initialize(char[],int*); void input(const char[] ,int&); void print ( const char*,const int); void growOlder (const char [], int* ); bool comparePeople(const char* ,const int*,const char*,const int*); int main(){ char name1[25]; char name2[25]; int age1; int age2; initialize (name1,&age1); initialize (name2,&age2); print(name1,*age1); print(name2,*age2); input(name1,age1); input(name2,age2); print(&name1,&age1); print(&name2,&age2); growOlder(name2,age2); if(comparePeople(name1,&age1,name2,&age2)) cout<<"Both People have the same name and age "<<endl; return 0; } void input(const char name[],int &age) { cout<<"Enter a name :"; cinname ; cout<<"Enter an age:"; cin>>age; cout<<endl; } void initialize ( char name[],int *age) { name=""; age=0; } void print ( const char name[],const int age ) { cout<<"The Value stored in variable name is :" < void growOlder(const char name[],int *age) { cout<< name <<" has grown one year older\n\n"; *age++; } bool comparePeople (const char *name1,const int *age1, const char *name2,const int *age2) { return(age1==age2 &&strcmp(name1,name2)); }

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  • how I can overcome this error C2679: binary '>>' : no operator found which takes a right-hand oper

    - by hussein abdullah
    #include <iostream> using std::cout; using std::cin; using std::endl; #include <cstring> void initialize(char[],int*); void input(const char[] ,int&); void print ( const char*,const int); void growOlder (const char [], int* ); bool comparePeople(const char* ,const int*,const char*,const int*); int main(){ char name1[25]; char name2[25]; int age1; int age2; initialize (name1,&age1); initialize (name2,&age2); print(name1,age1); print(name2,age2); input(name1,age1); input(name2,age2); print(name1,age1); print(name2,age2); growOlder(name2,&age2); if(comparePeople(name1,&age1,name2,&age2)) cout<<"Both People have the same name and age "<<endl; return 0; } void input(const char name[],int &age) { cout<<"Enter a name :"; cin>>name ; cout<<"Enter an age:"; cin>>age; cout<<endl; } void initialize ( char name[],int *age) { name[0]='\0'; *age=0; } void print ( const char name[],const int age ) { cout<<"The Value stored in variable name is :" <<name<<endl <<"The Value stored in variable age is :" <<age<<endl<<endl; } void growOlder(const char name[],int *age) { cout<< name <<" has grown one year older\n\n"; *age++; } bool comparePeople (const char *name1,const int *age1, const char *name2,const int *age2) { return(*age1==*age2 && !strcmp(name1,name2)); }

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  • C++ [] array operator with multiple arguments?

    - by genesys
    Can I define in C++ an array operator that takes multiple arguments? I tried it like this: const T& operator[](const int i, const int j, const int k) const{ return m_cells[k*m_resSqr+j*m_res+i]; } T& operator[](const int i, const int j, const int k){ return m_cells[k*m_resSqr+j*m_res+i]; } But I'm getting this error: error C2804 binary operator '[' has too many parameters

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  • How to layout class definition when inheriting from multiple interfaces

    - by gabr
    Given two interface definitions ... IOmniWorkItem = interface ['{3CE2762F-B7A3-4490-BF22-2109C042EAD1}'] function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); // procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; end; IOmniWorkItemEx = interface ['{3B48D012-CF1C-4B47-A4A0-3072A9067A3E}'] function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); // property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; ... what are your ideas of laying out class declaration that inherits from both of them? My current idea (but I don't know if I'm happy with it): TOmniWorkItem = class(TInterfacedObject, IOmniWorkItem, IOmniWorkItemEx) strict private FData : TOmniValue; FOnWorkItemDone : TOmniWorkItemDoneDelegate; FOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; FResult : TOmniValue; FUniqueID : int64; strict protected procedure FreeException; protected //IOmniWorkItem function GetData: TOmniValue; function GetResult: TOmniValue; function GetUniqueID: int64; procedure SetResult(const value: TOmniValue); protected //IOmniWorkItemEx function GetOnWorkItemDone: TOmniWorkItemDoneDelegate; function GetOnWorkItemDone_Asy: TOmniWorkItemDoneDelegate; procedure SetOnWorkItemDone(const Value: TOmniWorkItemDoneDelegate); procedure SetOnWorkItemDone_Asy(const Value: TOmniWorkItemDoneDelegate); public constructor Create(const data: TOmniValue; uniqueID: int64); destructor Destroy; override; public //IOmniWorkItem procedure Cancel; function DetachException: Exception; function FatalException: Exception; function IsCanceled: boolean; function IsExceptional: boolean; property Data: TOmniValue read GetData; property Result: TOmniValue read GetResult write SetResult; property UniqueID: int64 read GetUniqueID; public //IOmniWorkItemEx property OnWorkItemDone: TOmniWorkItemDoneDelegate read GetOnWorkItemDone write SetOnWorkItemDone; property OnWorkItemDone_Asy: TOmniWorkItemDoneDelegate read GetOnWorkItemDone_Asy write SetOnWorkItemDone_Asy; end; As noted in answers, composition is a good approach for this example but I'm not sure it applies in all cases. Sometimes I'm using multiple inheritance just to split read and write access to some property into public (typically read-only) and private (typically write-only) part. Does composition still apply here? I'm not really sure as I would have to move the property in question out from the main class and I'm not sure that's the correct way to do it. Example: // public part of the interface interface IOmniWorkItemConfig = interface function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; end; // private part of the interface IOmniWorkItemConfigEx = interface ['{42CEC5CB-404F-4868-AE81-6A13AD7E3C6B}'] function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end; // implementing class TOmniWorkItemConfig = class(TInterfacedObject, IOmniWorkItemConfig, IOmniWorkItemConfigEx) strict private FOnExecute : TOmniBackgroundWorkerDelegate; FOnRequestDone : TOmniWorkItemDoneDelegate; FOnRequestDone_Asy: TOmniWorkItemDoneDelegate; public constructor Create(defaults: IOmniWorkItemConfig = nil); public //IOmniWorkItemConfig function OnExecute(const aTask: TOmniBackgroundWorkerDelegate): IOmniWorkItemConfig; function OnRequestDone(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; function OnRequestDone_Asy(const aTask: TOmniWorkItemDoneDelegate): IOmniWorkItemConfig; public //IOmniWorkItemConfigEx function GetOnExecute: TOmniBackgroundWorkerDelegate; function GetOnRequestDone: TOmniWorkItemDoneDelegate; function GetOnRequestDone_Asy: TOmniWorkItemDoneDelegate; end;

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  • IsNumeric() Broken? Only up to a point.

    - by Phil Factor
    In SQL Server, probably the best-known 'broken' function is poor ISNUMERIC() . The documentation says 'ISNUMERIC returns 1 when the input expression evaluates to a valid numeric data type; otherwise it returns 0. ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($).'Although it will take numeric data types (No, I don't understand why either), its main use is supposed to be to test strings to make sure that you can convert them to whatever numeric datatype you are using (int, numeric, bigint, money, smallint, smallmoney, tinyint, float, decimal, or real). It wouldn't actually be of much use anyway, since each datatype has different rules. You actually need a RegEx to do a reasonably safe check. The other snag is that the IsNumeric() function  is a bit broken. SELECT ISNUMERIC(',')This cheerfully returns 1, since it believes that a comma is a currency symbol (not a thousands-separator) and you meant to say 0, in this strange currency.  However, SELECT ISNUMERIC(N'£')isn't recognized as currency.  '+' and  '-' is seen to be numeric, which is stretching it a bit. You'll see that what it allows isn't really broken except that it doesn't recognize Unicode currency symbols: It just tells you that one numeric type is likely to accept the string if you do an explicit conversion to it using the string. Both these work fine, so poor IsNumeric has to follow suit. SELECT  CAST('0E0' AS FLOAT)SELECT  CAST (',' AS MONEY) but it is harder to predict which data type will accept a '+' sign. SELECT  CAST ('+' AS money) --0.00SELECT  CAST ('+' AS INT)   --0SELECT  CAST ('+' AS numeric)/* Msg 8115, Level 16, State 6, Line 4 Arithmetic overflow error converting varchar to data type numeric.*/SELECT  CAST ('+' AS FLOAT)/*Msg 8114, Level 16, State 5, Line 5Error converting data type varchar to float.*/> So we can begin to say that the maybe IsNumeric isn't really broken, but is answering a silly question 'Is there some numeric datatype to which i can convert this string? Almost, but not quite. The bug is that it doesn't understand Unicode currency characters such as the euro or franc which are actually valid when used in the CAST function. (perhaps they're delaying fixing the euro bug just in case it isn't necessary).SELECT ISNUMERIC (N'?23.67') --0SELECT  CAST (N'?23.67' AS money) --23.67SELECT ISNUMERIC (N'£100.20') --1SELECT  CAST (N'£100.20' AS money) --100.20 Also the CAST function itself is quirky in that it cannot convert perfectly reasonable string-representations of integers into integersSELECT ISNUMERIC('200,000')       --1SELECT  CAST ('200,000' AS INT)   --0/*Msg 245, Level 16, State 1, Line 2Conversion failed when converting the varchar value '200,000' to data type int.*/  A more sensible question is 'Is this an integer or decimal number'. This cuts out a lot of the apparent quirkiness. We do this by the '+E0' trick. If we want to include floats in the check, we'll need to make it a bit more complicated. Here is a small test-rig. SELECT  PossibleNumber,         ISNUMERIC(CAST(PossibleNumber AS NVARCHAR(20)) + 'E+00') AS Hack,        ISNUMERIC (PossibleNumber + CASE WHEN PossibleNumber LIKE '%E%'                                          THEN '' ELSE 'E+00' END) AS Hackier,        ISNUMERIC(PossibleNumber) AS RawIsNumericFROM    (SELECT CAST(',' AS NVARCHAR(10)) AS PossibleNumber          UNION SELECT '£' UNION SELECT '.'         UNION SELECT '56' UNION SELECT '456.67890'         UNION SELECT '0E0' UNION SELECT '-'         UNION SELECT '-' UNION SELECT '.'         UNION  SELECT N'?' UNION SELECT N'¢'        UNION  SELECT N'?' UNION SELECT N'?34.56'         UNION SELECT '-345' UNION SELECT '3.332228E+09') AS examples Which gives the result ... PossibleNumber Hack Hackier RawIsNumeric-------------- ----------- ----------- ------------? 0 0 0- 0 0 1, 0 0 1. 0 0 1¢ 0 0 1£ 0 0 1? 0 0 0?34.56 0 0 00E0 0 1 13.332228E+09 0 1 1-345 1 1 1456.67890 1 1 156 1 1 1 I suspect that this is as far as you'll get before you abandon IsNumeric in favour of a regex. You can only get part of the way with the LIKE wildcards, because you cannot specify quantifiers. You'll need full-blown Regex strings like these ..[-+]?\b[0-9]+(\.[0-9]+)?\b #INT or REAL[-+]?\b[0-9]{1,3}\b #TINYINT[-+]?\b[0-9]{1,5}\b #SMALLINT.. but you'll get even these to fail to catch numbers out of range.So is IsNumeric() an out and out rogue function? Not really, I'd say, but then it would need a damned good lawyer.

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