Search Results

Search found 5377 results on 216 pages for 'explicit cast operator'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 56/216 | < Previous Page | 52 53 54 55 56 57 58 59 60 61 62 63  | Next Page >

  • Official names for pointer operators

    - by FredOverflow
    What are the official names for the operators * and & in the context of pointers? They seem to be frequently called dereference operator and address-of operator respectively, but unfortunately, the section on unary operators in the standard does not name them. I really don't want to name & address-of anymore, because & returns a pointer, not an address. (A pointer is a language mechanism, while an address is an implementation detail. Addresses are untyped, while pointers aren't, except for void*.) The standard is very clear about this: The result of the unary & operator is a pointer to its operand. Symmetry suggests to name & reference operator which is a little unfortunate because of the collision with references in C++. The fact that & returns a pointer suggests pointer operator. Are there any official sources that would confirm these (or other) namings?

    Read the article

  • How to do a STAR search in LINQ

    - by aNui
    I'm not sure about clarity of the STAR word. I'm implementing a search method using linq-to-object in c#. And I want to do a search with * (star) operator like most of search apps or web can do. e.g. If I typed "p*", results should be everything starting with "p". And it should work for prefix star, suffix star or star in the middle. And it would be great if the search can do with "-" (minus/NOT) operator or "+" (plus/OR) operator or "AND" operator Thanks in advance.

    Read the article

  • Sorting objects in Python

    - by Curious2learn
    I want to sort objects using by one of their attributes. As of now, I am doing it in the following way USpeople.sort(key=lambda person: person.utility[chosenCar],reverse=True) This works fine, but I have read that using operator.attrgetter() might be a faster way to achieve this sort. First, is this correct? Assuming that it is correct, how do I use operator.attrgetter() to achieve this sort? I tried, keyFunc=operator.attrgetter('utility[chosenCar]') USpeople.sort(key=keyFunc,reverse=True) However, I get an error saying that there is no attribute 'utility[chosenCar]'. The problem is that the attribute by which I want to sort is in a dictionary. For example, the utility attribute is in the following form: utility={chosenCar:25000,anotherCar:24000,yetAnotherCar:24500} I want to sort by the utility of the chosenCar using operator.attrgetter(). How could I do this? Thanks in advance.

    Read the article

  • Containers of reference_wrappers (comparison operators required?)

    - by kloffy
    If you use stl containers together with reference_wrappers of POD types, the following code works just fine: int i = 3; std::vector< boost::reference_wrapper<int> > is; is.push_back(boost::ref(i)); std::cout << (std::find(is.begin(),is.end(),i)!=is.end()) << std::endl; However, if you use non-POD types such as (contrived example): struct Integer { int value; bool operator==(const Integer& rhs) const { return value==rhs.value; } bool operator!=(const Integer& rhs) const { return !(*this == rhs); } }; It doesn't suffice to declare those comparison operators, instead you have to declare: bool operator==(const boost::reference_wrapper<Integer>& lhs, const Integer& rhs) { return boost::unwrap_ref(lhs)==rhs; } And possibly also: bool operator==(const Integer& lhs, const boost::reference_wrapper<Integer>& rhs) { return lhs==boost::unwrap_ref(rhs); } In order to get the equivalent code to work: Integer j = { 0 }; std::vector< boost::reference_wrapper<Integer> > js; js.push_back(boost::ref(j)); std::cout << (std::find(js.begin(),js.end(),j)!=js.end()) << std::endl; Now, I'm wondering if this is really the way it's meant to be done, since it seems impractical. It just seems there should be a simpler solution, e.g. templates: template<class T> bool operator==(const boost::reference_wrapper<T>& lhs, const T& rhs) { return boost::unwrap_ref(lhs)==rhs; } template<class T> bool operator==(const T& lhs, const boost::reference_wrapper<T>& rhs) { return lhs==boost::unwrap_ref(rhs); } There's probably a good reason why reference_wrapper behaves the way it does (possibly to accomodate non-POD types without comparison operators?). Maybe there already is an elegant solution and I just haven't found it.

    Read the article

  • Turn class "Interfaceable"

    - by scooterman
    Hi folks, On my company system, we use a class to represent beans. It is just a holder of information using boost::variant and some serialization/deserialization stuff. It works well, but we have a problem: it is not over an interface, and since we use modularization through dlls, building an interface for it is getting very complicated, since it is used in almost every part of our app, and sadly interfaces (abstract classes ) on c++ have to be accessed through pointers, witch makes almost impossible to refactor the entire system. Our structure is: dll A: interface definition through abstract class dll B: interface implementation there is a painless way to achieve that (maybe using templates, I don't know) or I should forget about making this work and simply link everything with dll B? thanks Edit: Here is my example. this is on dll A BeanProtocol is a holder of N dataprotocol itens, wich are acessed by a index. class DataProtocol; class UTILS_EXPORT BeanProtocol { public: virtual DataProtocol& get(const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void getFields(std::list<unsigned int>&) const { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void fromString(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toString() const { throw std::runtime_error("Not implemented"); } virtual void fromBinary(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toBinary() const { throw std::runtime_error("Not implemented"); } virtual BeanProtocol& operator=(const BeanProtocol&) { throw std::runtime_error("Not implemented"); } virtual bool operator==(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator!=(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator==(const char*) const { throw std::runtime_error("Not implemented"); } virtual bool hasKey(unsigned int field) const { throw std::runtime_error("Not implemented"); } }; the other class (named GenericBean) implements it. This is the only way I've found to make this work, but now I want to turn it in a truly interface and remove the UTILS_EXPORT (which is an _declspec macro), and finally remove the forced linkage of B with A.

    Read the article

  • How do I check if a SQL Server 2005 TEXT column is not null or empty using LINQ To Entities?

    - by emzero
    Hi there guys I'm new to LINQ and I'm trying to check whether a TEXT column is null or empty (as String.IsNullOrEmpty). from c in ... ... select new { c.Id, HasBio = !String.IsNullOrEmpty(c.bio) } Trying to use the above query produces an SqlException: Argument data type text is invalid for argument 1 of len function. The SQL generated is similar to the following: CASE WHEN ( NOT (([Extent2].[bio] IS NULL) OR (( CAST(LEN([Extent2].[bio]) AS int)) = 0))) THEN cast(1 as bit) WHEN (([Extent2].[bio] IS NULL) OR (( CAST(LEN([Extent2].[bio]) AS int)) = 0)) THEN cast(0 as bit) END AS [C1] LEN is not applicable to TEXT columns. I know DATALENGTH should be used for them... How can I force LINQ to produce such thing? Or any other workaround to test if a text column is null or empty??? Thanks!

    Read the article

  • Why is this default template parameter not allowed?

    - by Matt Joiner
    I have the following class: template <typename Type = void> class AlignedMemory { public: AlignedMemory(size_t alignment, size_t size) : memptr_(0) { int iret(posix_memalign((void **)&memptr_, alignment, size)); if (iret) throw system_error("posix_memalign"); } virtual ~AlignedMemory() { free(memptr_); } operator Type *() const { return memptr_; } Type *operator->() const { return memptr_; } //operator Type &() { return *memptr_; } //Type &operator[](size_t index) const; private: Type *memptr_; }; And attempt to instantiate an automatic variable like this: AlignedMemory blah(512, 512); This gives the following error: src/cpfs/entry.cpp:438: error: missing template arguments before ‘buf’ What am I doing wrong? Is void not an allowed default parameter?

    Read the article

  • Deployment of broadband network

    - by sthustfo
    Hi all, My query is related to broadband network deployment. I have a DSL modem connection provided by my operator. Now the DSL modem has a built-in NAT and DHCP server, hence it allocates IP addresses to any client devices (laptops, PC, mobile) that connect to it. However, the DSL modem also gets a public IP address X that is provisioned by the operator. My question is Whether this IP address X provisioned by operator is an IP address that is directly on the public Internet? Is it likely (practical scenario) that my broadband operator will put in one more NAT+DHCP server and provide IP addresses to all the modems within his broadband network. In this case, the IP addresses allotted to the modem devices will not be directly on the public Internet. Thanks in advance.

    Read the article

  • convert MsSql StoredPorcedure to MySql

    - by karthik
    I need to covert the following SP of MsSql To MySql. I am new to MySql.. Help needed. CREATE PROC InsertGenerator (@tableName varchar(100)) as --Declare a cursor to retrieve column specific information --for the specified table DECLARE cursCol CURSOR FAST_FORWARD FOR SELECT column_name,data_type FROM information_schema.columns WHERE table_name = @tableName OPEN cursCol DECLARE @string nvarchar(3000) --for storing the first half --of INSERT statement DECLARE @stringData nvarchar(3000) --for storing the data --(VALUES) related statement DECLARE @dataType nvarchar(1000) --data types returned --for respective columns SET @string='INSERT '+@tableName+'(' SET @stringData='' DECLARE @colName nvarchar(50) FETCH NEXT FROM cursCol INTO @colName,@dataType IF @@fetch_status<0 begin print 'Table '+@tableName+' not found, processing skipped.' close curscol deallocate curscol return END WHILE @@FETCH_STATUS=0 BEGIN IF @dataType in ('varchar','char','nchar','nvarchar') BEGIN SET @stringData=@stringData+'''''''''+ isnull('+@colName+','''')+'''''',''+' END ELSE if @dataType in ('text','ntext') --if the datatype --is text or something else BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast('+@colName+' as varchar(2000)),'''')+'''''',''+' END ELSE IF @dataType = 'money' --because money doesn't get converted --from varchar implicitly BEGIN SET @stringData=@stringData+'''convert(money,''''''+ isnull(cast('+@colName+' as varchar(200)),''0.0000'')+''''''),''+' END ELSE IF @dataType='datetime' BEGIN SET @stringData=@stringData+'''convert(datetime,''''''+ isnull(cast('+@colName+' as varchar(200)),''0'')+''''''),''+' END ELSE IF @dataType='image' BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast(convert(varbinary,'+@colName+') as varchar(6)),''0'')+'''''',''+' END ELSE --presuming the data type is int,bit,numeric,decimal BEGIN SET @stringData=@stringData+'''''''''+ isnull(cast('+@colName+' as varchar(200)),''0'')+'''''',''+' END SET @string=@string+@colName+',' FETCH NEXT FROM cursCol INTO @colName,@dataType END

    Read the article

  • Turning temporary stringstream to c_str() in single statement

    - by AshleysBrain
    Consider the following function: void f(const char* str); Suppose I want to generate a string using stringstream and pass it to this function. If I want to do it in one statement, I might try: f((std::ostringstream() << "Value: " << 5).str().c_str()); // error This gives an error: 'str()' is not a member of 'basic_ostream'. OK, so operator<< is returning ostream instead of ostringstream - how about casting it back to an ostringstream? 1) Is this cast safe? f(static_cast<std::ostringstream&>(std::ostringstream() << "Value: " << 5).str().c_str()); // incorrect output Now with this, it turns out for the operator<<("Value: ") call, it's actually calling ostream's operator<<(void*) and printing a hex address. This is wrong, I want the text. 2) Why does operator<< on the temporary std::ostringstream() call the ostream operator? Surely the temporary has a type of 'ostringstream' not 'ostream'? I can cast the temporary to force the correct operator call too! f(static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << "Value: " << 5).str().c_str()); This appears to work and passes "Value: 5" to f(). 3) Am I relying on undefined behavior now? The casts look unusual. I'm aware the best alternative is something like this: std::ostringstream ss; ss << "Value: " << 5; f(ss.str().c_str()); ...but I'm interested in the behavior of doing it in one line. Suppose someone wanted to make a (dubious) macro: #define make_temporary_cstr(x) (static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << x).str().c_str()) // ... f(make_temporary_cstr("Value: " << 5)); Would this function as expected?

    Read the article

  • Internal class and access to external members.

    - by Knowing me knowing you
    I always thought that internal class has access to all data in its external class but having code: template<class T> class Vector { template<class T> friend std::ostream& operator<<(std::ostream& out, const Vector<T>& obj); private: T** myData_; std::size_t myIndex_; std::size_t mySize_; public: Vector():myData_(nullptr), myIndex_(0), mySize_(0) { } Vector(const Vector<T>& pattern); void insert(const T&); Vector<T> makeUnion(const Vector<T>&)const; Vector<T> makeIntersection(const Vector<T>&)const; class Iterator : public std::iterator<std::bidirectional_iterator_tag,T> { private: T** itData_; public: Iterator()//<<<<<<<<<<<<<------------COMMENT { /*HERE I'M TRYING TO USE ANY MEMBER FROM Vector<T> AND I'M GETTING ERR SAYING: ILLEGAL CALL OF NON-STATIC MEMBER FUNCTION*/} Iterator(T** ty) { itData_ = ty; } Iterator operator++() { return ++itData_; } T operator*() { return *itData_[0]; } bool operator==(const Iterator& obj) { return *itData_ == *obj.itData_; } bool operator!=(const Iterator& obj) { return *itData_ != *obj.itData_; } bool operator<(const Iterator& obj) { return *itData_ < *obj.itData_; } }; typedef Iterator iterator; iterator begin()const { assert(mySize_ > 0); return myData_; } iterator end()const { return myData_ + myIndex_; } }; See line marked as COMMENT. So can I or I can't use members from external class while in internal class? Don't bother about naming, it's not a Vector it's a Set. Thank you.

    Read the article

  • heterogeneous comparisons in python3

    - by Matt Anderson
    I'm 99+% still using python 2.x, but I'm trying to think ahead to the day when I switch. So, I know that using comparison operators (less/greater than, or equal to) on heterogeneous types that don't have a natural ordering is no longer supported in python3.x -- instead of some consistent (but arbitrary) result we raise TypeError instead. I see the logic in that, and even mostly think its a good thing. Consistency and refusing to guess is a virtue. But what if you essentially want the python2.x behavior? What's the best way to go about getting it? For fun (more or less) I was recently implementing a Skip List, a data structure that keeps its elements sorted. I wanted to use heterogeneous types as keys in the data structure, and I've got to compare keys to one another as I walk the data structure. The python2.x way of comparing makes this really convenient -- you get an understandable ordering amongst elements that have a natural ordering, and some ordering amongst those that don't. Consistently using a sort/comparison key like (type(obj).__name__, obj) has the disadvantage of not interleaving the objects that do have a natural ordering; you get all your floats clustered together before your ints, and your str-derived class separates from your strs. I came up with the following: import operator def hetero_sort_key(obj): cls = type(obj) return (cls.__name__+'_'+cls.__module__, obj) def make_hetero_comparitor(fn): def comparator(a, b): try: return fn(a, b) except TypeError: return fn(hetero_sort_key(a), hetero_sort_key(b)) return comparator hetero_lt = make_hetero_comparitor(operator.lt) hetero_gt = make_hetero_comparitor(operator.gt) hetero_le = make_hetero_comparitor(operator.le) hetero_ge = make_hetero_comparitor(operator.gt) Is there a better way? I suspect one could construct a corner case that this would screw up -- a situation where you can compare type A to B and type A to C, but where B and C raise TypeError when compared, and you can end up with something illogical like a > b, a < c, and yet b > c (because of how their class names sorted). I don't know how likely it is that you'd run into this in practice.

    Read the article

  • Potential g++ template bug?

    - by Evan Teran
    I've encountered some code which I think should compile, but doesn't. So I'm hoping some of the local standards experts here at SO can help :-). I basically have some code which resembles this: #include <iostream> template <class T = int> class A { public: class U { }; public: U f() const { return U(); } }; // test either the work around or the code I want... #ifndef USE_FIX template <class T> bool operator==(const typename A<T>::U &x, int y) { return true; } #else typedef A<int> AI; bool operator==(const AI::U &x, int y) { return true; } #endif int main() { A<int> a; std::cout << (a.f() == 1) << std::endl; } So, to describe what is going on here. I have a class template (A) which has an internal class (U) and at least one member function which can return an instance of that internal class (f()). Then I am attempting to create an operator== function which compares this internal type to some other type (in this case an int, but it doesn't seem to matter). When USE_FIX is not defined I get the following error: test.cc: In function 'int main()': test.cc:27:25: error: no match for 'operator==' in 'a.A<T>::f [with T = int]() == 1' Which seems odd, because I am clearly (I think) defining a templated operator== which should cover this, in fact if I just do a little of the work for the compiler (enable USE_FIX), then I no longer get an error. Unfortunately, the "fix" doesn't work generically, only for a specific instantiation of the template. Is this supposed to work as I expected? Or is this simply not allowed? BTW: if it matters I am using gcc 4.5.2.

    Read the article

  • Simple syntax error still eluding me.

    - by melee
    Here is the header for a class I started: #ifndef CANVAS_ #define CANVAS_ #include <iostream> #include <iomanip> #include <string> #include <stack> class Canvas { public: Canvas(); void Paint(int R, int C, char Color); const int Nrow; const int Ncol; string Title; int image[][100]; stack<int> path; struct PixelCoordinates { unsigned int r; unsigned int c; } position; Canvas operator<< (const Canvas& One ); Canvas operator>>( Canvas& One ); }; /*----------------------------------------------------------------------------- Name: operator<< Purpose: Put a Canvas into an output stream -----------------------------------------------------------------------------*/ ostream& operator<<( ostream& Out, const Canvas& One ) { Out << One.Title << endl; Out << "Rows: " << One.Nrow << " Columns: " << One.Ncol << endl; int i,j; for( i=0; i<One.Nrow; i++) { cout<<"\n\n\n"; cout<< " COLUMN\n"; cout<< " 1 2 3"; for(i=0;i<One.Nrow;i++) { cout<<"\nROW "<<i+1; for(j=0;j<One.Ncol;j++) cout<< One.image[i][j]; } } return Out; } /*----------------------------------------------------------------------------- Name: operator>> Purpose: Get a Canvas from an input stream -----------------------------------------------------------------------------*/ istream& operator>>( istream& In, Canvas& One ) { // string Line; // int Place = 0; // { // In >> Line; // if (In.good()) // { // One.image[Place][0] = Line; // Place++; // } // return In; #endif Here is my implementation file for class Canvas: using namespace std; #include <iostream> #include <iomanip> #include <string> #include <stack> #include "proj05.canvas.h" //----------------Constructor----------------// Canvas::Canvas() { Title = ""; Nrow = 0; Ncol = 0; image[][100] = {}; position.r = 0; position.c = 0; } //-------------------Paint------------------// void Canvas::Paint(int R, int C, char Color) { cout << "Paint to be implemented" << endl; } And the errors I'm getting are these: proj05.canvas.cpp: In function 'std::istream& operator>>(std::istream&, Canvas&)': proj05.canvas.cpp:11: error: expected `;' before '{' token proj05.canvas.cpp:24: error: expected `}' at end of input From my limited experience, they look like simple syntax errors but for the life of me, I cannot see what I am missing. I know putting a ; at the end of Canvas::Canvas() is wrong but that seems to be what it expects. Could someone please clarify for me? (Also, I know much of the code for the << and operator definitions look terrible, but unless that is the specific reason for the error please do not address it. This is a draft :) )

    Read the article

  • Are there any C++ tools that detect misuse of static_cast, dynamic_cast, and reinterpret_cast?

    - by chrisp451
    The answers to the following question describe the recommended usage of static_cast, dynamic_cast, and reinterpret_cast in C++: http://stackoverflow.com/questions/332030/when-should-static-cast-dynamic-cast-and-reinterpret-cast-be-used Do you know of any tools that can be used to detect misuse of these kinds of cast? Would a static analysis tool like PC-Lint or Coverity Static Analysis do this? The particular case that prompted this question was the inappropriate use of static_cast to downcast a pointer, which the compiler does not warn about. I'd like to detect this case using a tool, and not assume that developers will never make this mistake.

    Read the article

  • Access Violation When Accessing an STL Object Through A Pointer or Reference In A Different DLL or E

    - by Yan Cheng CHEOK
    I experience the following problem while using legacy VC6. I just cann't switch to modern compiler, as I am working on a legacy code base. http://support.microsoft.com/kb/172396 Since there are no way to export map, my planned workaround is using static linking instead of dynamic linking. I was wondering whether you all had encountered the similar situation? What is your workaround for this? Another workaround is to create wrapper class around the stl map, to ensure creation and accessing stl map, are within the same DLL space. Note that, fun0, which uses wrapper class will just work fine. fun1 will crash. Here is the code example : // main.cpp. Compiled it as exe. #pragma warning (disable : 4786) #include <map> #include <string> template <class K, class V> class __declspec(dllimport) map_wrapper { public: map_wrapper(); ~map_wrapper(); map_wrapper(const map_wrapper&); map_wrapper& operator=(const map_wrapper&); V& operator[](const K&); const V& operator[](const K&) const; const V& get(const K&) const; void put(const K&, const V&); int size() const; private: std::map<K, V> *m; }; __declspec(dllimport) void fun0(map_wrapper<std::string, int>& m); __declspec(dllimport) void fun1(std::map<std::string, int>& m); int main () { map_wrapper<std::string, int> m0; std::map<std::string, int> m1; m0["hello"] = 888; m1["hello"] = 888; // Safe. The we create std::map and access map both in dll space. fun0(m0); // Crash! The we create std::map in exe space, and access map in dll space. fun1(m1); return 0; } // dll.cpp. Compiled it as dynamic dll. #pragma warning (disable : 4786) #include <map> #include <string> #include <iostream> /* In map_wrapper.h */ template <class K, class V> class __declspec(dllexport) map_wrapper { public: map_wrapper(); ~map_wrapper(); map_wrapper(const map_wrapper&); map_wrapper& operator=(const map_wrapper&); V& operator[](const K&); const V& operator[](const K&) const; const V& get(const K&) const; void put(const K&, const V&); int size() const; private: std::map<K, V> *m; }; /* End */ /* In map_wrapper.cpp */ template <class K, class V> map_wrapper<K, V>::map_wrapper() : m(new std::map<K, V>()) { } template <class K, class V> map_wrapper<K, V>::~map_wrapper() { delete m; } template <class K, class V> map_wrapper<K, V>::map_wrapper(const map_wrapper<K, V>& map) : m(new std::map<K, V>(*(map.m))) { } template <class K, class V> map_wrapper<K, V>& map_wrapper<K, V>::operator=(const map_wrapper<K, V>& map) { std::map<K, V>* tmp = this->m; this->m = new std::map<K, V>(*(map.m)); delete tmp; return *this; } template <class K, class V> V& map_wrapper<K, V>::operator[](const K& key) { return (*this->m)[key]; } template <class K, class V> const V& map_wrapper<K, V>::operator[](const K& key) const { return (*this->m)[key]; } template <class K, class V> const V& map_wrapper<K, V>::get(const K& key) const { return (*this->m)[key]; } template <class K, class V> void map_wrapper<K, V>::put(const K& key, const V& value) { (*this->m)[key] = value; } template <class K, class V> int map_wrapper<K, V>::size() const { return this->m->size(); } // See : http://www.parashift.com/c++-faq-lite/templates.html#faq-35.15 // [35.15] How can I avoid linker errors with my template classes? template class __declspec(dllexport) map_wrapper<std::string, int>; /* End */ __declspec(dllexport) void fun0(map_wrapper<std::string, int>& m) { std::cout << m["hello"] << std::endl; } __declspec(dllexport) void fun1(std::map<std::string, int>& m) { std::cout << m["hello"] << std::endl; }

    Read the article

  • Dynamic casting using a generic interface

    - by Phil Whittaker
    Hi Is there any way to cast to a dynamic generic interface.. Site s = new Site(); IRepository<Site> obj = (IRepository<s.GetType()>)ServiceLocator.Current.GetInstance(t) obviously the above won't compile with this cast. Is there anyway to do a dynamic cast of a generic interface. I have tried adding a non generic interface but the system is looses objects in the Loc container. Thanks Phil

    Read the article

  • Problem convert column values from VARCHAR(n) to DECIMAL

    - by Kevin Babcock
    I have a SQL Server 2000 database with a column of type VARCHAR(255). All the data is either NULL, or numeric data with up to two points of precision (e.g. '11.85'). I tried to run the following T-SQL query but received the error 'Error converting data type varchar to numeric' SELECT CAST([MyColumn] AS DECIMAL) FROM [MyTable]; I tried a more specific cast, which also failed. SELECT CAST([MyColumn] AS DECIMAL(6,2)) FROM [MyTable]; I also tried the following to see if any data is non-numeric, and the only values returned were NULL. SELECT ISNUMERIC([MyColumn]), [MyColumn] FROM [MyTable] WHERE ISNUMERIC([MyColumn]) = 0; I tried to convert to other data types, such as FLOAT and MONEY, but only MONEY was successful. So I tried the following: SELECT CAST(CAST([MyColumn] AS MONEY) AS DECIMAL) FROM [MyTable]; ...which worked just fine. Any ideas why the original query failed? Will there be a problem if I first convert to MONEY and then to DECIMAL? Thanks!

    Read the article

  • Intime and OutTime for the Modified date

    - by Jash
    Question is already posted on June 4, but still am not get the Proper answer Again Table Structure: T_Person – Table 1 CARDNO 168 471 488 247 519 518 331 240 518 386 441 331 T_Cardevent – Table 2 CARDEVENTDATE CARDEVENTTIME 20090225 163932 20090225 164630 20090225 165027 20090225 165137 20090225 165147 20090225 165715 20090225 165749 20090303 162059 20090303 162723 20090303 155029 20090303 155707 20090303 162824 Query SELECT CARDNO, CARDEVENTDATE, (1000000 * CAST (CARDEVENTDATE AS BIGINT) + CAST (CARDEVENTTIME AS BIGINT) - 30001) / 1000000 AS CardEvenDateAdjusted, CARDEVENTTIME FROM T_CARDEVENT WHERE (CARDEVENTDATE > 20090601) GROUP BY CARDNO, CARDEVENTDATE, CARDEVENTTIME, (1000000 * CAST(CARDEVENTDATE AS BIGINT) + CAST(CARDEVENTTIME AS BIGINT) - 30001) / 1000000 ORDER BY CARDNO, CARDEVENDATEADJUSTED From this above query date is displaying correctly according to that time 03:00:01 to 03:00:00 How can I get min (time) and Max (time) for the adjusted date? I need the sql query for the above condition. Help me? Urgent Please

    Read the article

  • What does this structure actually do?

    - by LGTrader
    I found this structure code in a Julia Set example from a book on CUDA. I'm a newbie C programmer and cannot get my head around what it's doing, nor have I found the right thing to read on the web to clear it up. Here's the structure: struct cuComplex { float r; float i; cuComplex( float a, float b ) : r(a), i(b) {} float magnitude2( void ) { return r * r + i * i; } cuComplex operator*(const cuComplex& a) { return cuComplex(r*a.r - i*a.i, i*a.r + r*a.i); } cuComplex operator+(const cuComplex& a) { return cuComplex(r+a.r, i+a.i); } }; and it's called very simply like this: cuComplex c(-0.8, 0.156); cuComplex a(jx, jy); int i = 0; for (i=0; i<200; i++) { a = a * a + c; if (a.magnitude2() > 1000) return 0; } return 1; So, the code did what? Defined something of structure type 'cuComplex' giving the real and imaginary parts of a number. (-0.8 & 0.156) What is getting returned? (Or placed in the structure?) How do I work through the logic of the operator stuff in the struct to understand what is actually calculated and held there? I think that it's probably doing recursive calls back into the stucture float magnitude2 (void) { return return r * r + i * i; } probably calls the '*' operator for r and again for i, and then the results of those two operations call the '+' operator? Is this correct and what gets returned at each step? Just plain confused. Thanks!

    Read the article

  • Macro and array crossing

    - by Thomas
    I am having a problem with a lisp macro. I would like to create a macro which generate a switch case according to an array. Here is the code to generate the switch-case: (defun split-elem(val) `(,(car val) ',(cdr val))) (defmacro generate-switch-case (var opts) `(case ,var ,(mapcar #'split-elem opts))) I can use it with a code like this: (generate-switch-case onevar ((a . A) (b . B))) But when I try to do something like this: (defparameter *operators* '((+ . OPERATOR-PLUS) (- . OPERATOR-MINUS) (/ . OPERATOR-DIVIDE) (= . OPERATOR-EQUAL) (* . OPERATOR-MULT))) (defmacro tokenize (data ops) (let ((sym (string->list data))) (mapcan (lambda (x) (generate-switch-case x ops)) sym))) (tokenize data *operators*) I got this error: *** - MAPCAR: A proper list must not end with OPS. But I don't understand why. When I print the type of ops I get SYMBOL I was expecting CONS, is it related? Also, for my function tokenize how many times the lambda is evaluated (or the macro expanded)?

    Read the article

  • Datatype Conversion

    - by user87
    I am trying to execute the following Query select distinct pincode as Pincode,CAST(Date_val as DATE) as Date, SUM(cast(megh_38 as int)) as 'Postage Realized in Cash', SUM(cast(megh_39 as int)) as 'MO Commission', from dbo.arrow_dtp_upg group by pincode,Date_Val but I am getting an error "Conversion failed when converting the nvarchar value '82.25' to data type int." Am I using a wrong data type?

    Read the article

  • Why does concatenating strings in the argument of EXEC sometimes cause a syntax error in T-SQL?

    - by Tim Goodman
    In MS SQL Server Management Studio 2005, running this code EXEC('SELECT * FROM employees WHERE employeeID = ' + CAST(3 AS VARCHAR)) gives this error: Incorrect syntax near 'CAST' However, if I do this, it works: DECLARE @temp VARCHAR(4000) SET @temp = 'SELECT * FROM employees WHERE employeeID = ' + CAST(3 AS VARCHAR) EXEC(@temp) I found an explanation here: http://stackoverflow.com/questions/1044831/t-sql-cannot-pass-concatenated-string-as-argument-to-stored-procedure According to the accepted answer, EXEC can take a local variable or a value as its argument, but not an expression. However, if that's the case, why does this work: DECLARE @temp VARCHAR(4000) SET @temp = CAST(3 AS VARCHAR) EXEC('SELECT * FROM employees WHERE employeeID = ' + @temp) 'SELECT * FROM employees WHERE employeeID = ' + @temp sure looks like an expression to me, but the code executes with no errors.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 52 53 54 55 56 57 58 59 60 61 62 63  | Next Page >