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  • Script throwing unexpected operator when using mysqldump

    - by Astron
    A portion of a script I use to backup MySQL databases has stopped working correctly after upgrading a Debian box to 6.0 Squeeze. I have tested the backup code via CLI and it works fine. I believe it is in the selection of the databases before the backup occurs, possibly something to do with the $skipdb variable. If there is a better way to perform the function then I'm will to try something new. Any insight would be greatly appreciated. $ sudo ./script.sh [: 138: information_schema: unexpected operator [: 138: -1: unexpected operator [: 138: mysql: unexpected operator [: 138: -1: unexpected operator Using bash -x script here is one of the iterations: + for db in '$DBS' + skipdb=-1 + '[' test '!=' '' ']' + for i in '$IGGY' + '[' mysql == test ']' + : + '[' -1 == -1 ']' ++ /bin/date +%F + FILE=/backups/hostname.2011-03-20.mysql.mysql.tar.gz + '[' no = yes ']' + /usr/bin/mysqldump --single-transaction -u root -h localhost '-ppassword' mysql + /bin/tar -czvf /backups/hostname.2011-03-20.mysql.mysql.tar.gz mysql.sql mysql.sql + rm -f mysql.sql Here is the code. if [ $MYSQL_UP = "yes" ]; then echo "MySQL DUMP" >> /tmp/update.log echo "--------------------------------" >> /tmp/update.log DBS="$($MYSQL -u $MyUSER -h $MyHOST -p"$MyPASS" -Bse 'show databases')" for db in $DBS do skipdb=-1 if [ "$IGGY" != "" ] ; then for i in $IGGY do [ "$db" == "$i" ] && skipdb=1 || : done fi if [ "$skipdb" == "-1" ] ; then FILE="$DEST$HOST.`$DATE +"%F"`.$db.mysql.tar.gz" if [ $ENCRYPT = "yes" ]; then $MYSQLDUMP -u $MyUSER -h $MyHOST -p"$MyPASS" $db > $db.sql && $TAR -czvf - $db.sql | $OPENSSL enc -aes-256-cbc -salt -out $FILE.enc -k $ENC_PASS && rm -f $db.sql else $MYSQLDUMP --single-transaction -u $MyUSER -h $MyHOST -p"$MyPASS" $db > $db.sql && $TAR -czvf $FILE $db.sql && rm -f $db.sql fi fi done fi

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  • Guru of the Week 2 no match for the operator==

    - by Adam
    From Guru of the Week 2. We have the function: string FindAddr(const list<Employee> l, string name) { for( list<Employee>::const_iterator i = l.begin(); i != l.end(); i++) { if( *i == name ) // here will be compilation error { return (*i).addr; } } return ""; } I added dummy Employee class to that: class Employee { string n; public: string addr; Employee(string name) : n(name) {} Employee() {} string name() const { return n; } operator string() { return n; } }; And got compilation error: error: no match for ‘operator==’ in ‘i.std::_List_iterator<_Tp>::operator* [with _Tp = Employee]() == name’ It works only if add operator== to Employee. But, Herb Sutter wrote that: The Employee class isn't shown, but for this to work it must either have a conversion to string or a conversion ctor taking a string. But Employee has a conversion function and conversion constructor as well. GCC version 4.4.3. Compiled normally, g++ file.cpp without any flags. There should be implicit conversion and it should work, why it doesn't?

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  • operator << : std::cout << i << (i << 1);

    - by Oops
    Hi, I use the stream operator << and the bit shifting operator << in one line. I am a bit confused, why does code A) not produce the same output than code B)? A) int i = 4; std::cout << i << " " << (i << 1) << std::endl; //4 8 B) myint m = 4; std::cout << m << " " << (m << 1) << std::endl; //8 8 class myint: class myint { int i; public: myint(int ii) { i = ii; } inline myint operator <<(int n){ i = i << n; return *this; } inline operator int(){ return i; } }; thanks in advance Oops

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  • Different behaviour of method overloading in C#

    - by Wondering
    Hi All, I was going through C# Brainteasers(http://www.yoda.arachsys.com/csharp/teasers.html) and came accross one question:what should be the o/p of below code class Base { public virtual void Foo(int x) { Console.WriteLine ("Base.Foo(int)"); } } class Derived : Base { public override void Foo(int x) { Console.WriteLine ("Derived.Foo(int)"); } public void Foo(object o) { Console.WriteLine ("Derived.Foo(object)"); } } class Test { static void Main() { Derived d = new Derived(); int i = 10; d.Foo(i); // it prints ("Derived.Foo(object)" } } but if I change the code to enter code here class Derived { public void Foo(int x) { Console.WriteLine("Derived.Foo(int)"); } public void Foo(object o) { Console.WriteLine("Derived.Foo(object)"); } } class Program { static void Main(string[] args) { Derived d = new Derived(); int i = 10; d.Foo(i); // prints Derived.Foo(int)"); Console.ReadKey(); } } I want to why the o/p is getting changde when we are inheriting vs not inheriting , why method overloading is behaving differently in both the cases

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  • defining < operator for map of list iterators

    - by Adrian
    I'd like to use iterators from an STL list as keys in a map. For example: using namespace std; list<int> l; map<list<int>::const_iterator, int> t; int main(int argv, char * argc) { l.push_back(1); t[l.begin()] = 5; } However, list iterators do not have a comparison operator defined (in contrast to random access iterators), so compiling the above code results in an error: /usr/include/c++/4.2.1/bits/stl_function.h:227: error: no match for ‘operator<’ in ‘__x < __y’ If the list is changed to a vector, a map of vector const_iterators compiles fine. What is the appropriate way to define the operator < for list::const_iterator?

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  • Allow member to be const while still supporting operator= on the class

    - by LeopardSkinPillBoxHat
    I have several members in my class which are const and can therefore only be initialised via the initialiser list like so: class MyItemT { public: MyItemT(const MyPacketT& aMyPacket, const MyInfoT& aMyInfo) : mMyPacket(aMyPacket), mMyInfo(aMyInfo) { } private: const MyPacketT mMyPacket; const MyInfoT mMyInfo; }; My class can be used in some of our internally defined container classes (e.g. vectors), and these containers require that operator= is defined in the class. Of course, my operator= needs to do something like this: MyItemT& MyItemT::operator=(const MyItemT& other) { mMyPacket = other.mPacket; mMyInfo = other.mMyInfo; return *this; } which of course doesn't work because mMyPacket and mMyInfo are const members. Other than making these members non-const (which I don't want to do), any ideas about how I could fix this?

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  • Concatenation Operator

    - by Chaitanya
    This might be a silly question but it struck me, and here i ask. <?php $x="Hi"; $y=" There"; $z = $x.$y; $a = "$x$y"; echo "$z"."<br />"."$a"; ?> $z uses the traditional concatenation operator provided by php and concatenates, conversely $a doesn't, My questions: by not using the concatenation operator, does it effect the performance? If it doesn't why at all have the concatenation operator. Why have 2 modes of implementation when one does the work?

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  • Concatenation Operator - PHP

    - by Chaitanya
    This might be a silly question but it struck me, and here i ask. <?php $x="Hi"; $y=" There"; $z = $x.$y; $a = "$x$y"; echo "$z"."<br />"."$a"; ?> $z uses the traditional concatenation operator provided by php and concatenates, conversely $a doesn't, My questions: a. by not using the concatenation operator, does it effect the performance? b. If it doesn't why at all have the concatenation operator. c. Why have 2 modes of implementation when one does the work?

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  • Understanding pattern matching with cons operator

    - by Mathias
    In "Programming F#" I came across a pattern-matching like this one (I simplified a bit): let rec len list = match list with | [] -> 0 | [_] -> 1 | head :: tail -> 1 + len tail;; Practically, I understand that the last match recognizes the head and tail of the list. Conceptually, I don't get why it works. As far as I understand, :: is the cons operator, which appends a value in head position of a list, but it doesn't look to me like it is being used as an operator here. Should I understand this as a "special syntax" for lists, where :: is interpreted as an operator or a "match pattern" depending on context? Or can the same idea be extended for types other than lists, with other operators?

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  • Should I make OR operator to return const reference or just reference

    - by Yan Cheng CHEOK
    class error_code { public: error_code() : hi(0), lo(0) {} error_code(__int64 lo) : hi(0), lo(lo) {} error_code(__int64 hi, __int64 lo) : hi(hi), lo(lo) {} error_code& operator|=(const error_code &e) { this->hi |= e.hi; this->lo |= e.lo; return *this; } __int64 hi; __int64 lo; }; error_code operator|(const error_code& e0, const error_code& e1) { return error_code(e0.hi | e1.hi, e0.lo | e1.lo); } int main() { error_code e0(1); error_code e1(2); e0 |= e1; } I was wondering, whether I should make operator|= to return a const error_code& or error_code& ?

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  • Does dynamic_cast work inside overloaded operator delete ?

    - by iammilind
    I came across this: struct Base { void* operator new (size_t); void operator delete (void*); virtual ~Base () {} // <--- polymorphic }; struct Derived : Base {}; void Base::operator delete (void *p) { Base *pB = static_cast<Base*>(p); if(dynamic_cast<Derived*>(pB) != 0) { /* ... NOT reaching here ? ... */ } free(p); } Now if we do, Base *p = new Derived; delete p; Surprisingly, the condition inside the Base::delete is not satisfied Am I doing anything wrong ? Or casting from void* looses the information of Derived* ?

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  • (C++) What's the difference between these overloaded operator functions?

    - by cv3000
    What is the difference between these two ways of overloading the != operator below. Which is consider better? Class Test { ...// private: int iTest public: BOOL operator==(const &Test test) const; BOOL operator!=(const &Test test) const; } BOOL operator==(const &Test test) const { return (iTest == test.iTest); } //overload function 1 BOOL Test::operator!=(const &Test test) const { return !operator==(test); } //overload function 2 BOOL Test::operator!=(const &Test test) const { return (iTest != test.iTest); } I've just recently seen function 1's syntax for calling a sibling operator function and wonder if writing it that way provides any benefits.

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  • Why can't we have an immutable version of operator[] for map

    - by Yan Cheng CHEOK
    The following code works fine : std::map<int, int>& m = std::map<int, int>(); int i = m[0]; But not the following code : // error C2678: binary '[' : no operator... const std::map<int, int>& m = std::map<int, int>(); int i = m[0]; Most of the time, I prefer to make most of my stuff to become immutable, due to reason : http://www.javapractices.com/topic/TopicAction.do?Id=29 I look at map source code. It has mapped_type& operator[](const key_type& _Keyval) Is there any reason, why std::map unable to provide const mapped_type& operator[](const key_type& _Keyval) const

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  • Is the "==" operator required to be defined to use std::find

    - by user144182
    Let's say I have: class myClass std::list<myClass> myList where myClass does not define the == operator and only consists of public fields. In both VS2010 and VS2005 the following does not compile: myClass myClassVal = myList.front(); std::find( myList.begin(), myList.end(), myClassVal ) complaining about lack of == operator. I naively assumed it would do a value comparison of the myClass object's public members, but I am almost positive this is not correct. I assume if I define a == operator or perhaps use a functor instead, it will solve the problem. Alternatively, if my list was holding pointers instead of values, the comparison would work. Is this right or should I be doing something else?

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  • Entity Framework with SQL Server 2000 (APPLY Operator) issue

    - by How Lun
    Hello, I have a simple Linq query below: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .Count(); This query works find with SQL Server 2005 and above. But, this start to give headache when I hooked the EF to SQL Server 2000. Because EF is using APPLY operator which only SQL Server 2005 and above can be supported. I do not know why the hell EF is using APPLy operator instead of sub queries. My current work around is: var seq = (from n in GetObjects() select n.SomeKey) .Distinct() .ToList() .Count(); But, I can forsee more problems to come. The above query is just a simple one. Did anyone come across such issue? And how you guys work around it? Or is there a way to force EF not to use APPLY operator? Any help will be very much appreciated. How Lun.

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  • When is #include <new> library required in C++?

    - by Czarak
    Hi, According to this reference entry for operator new ( http://www.cplusplus.com/reference/std/new/operator%20new/ ) : Global dynamic storage operator functions are special in the standard library: All three versions of operator new are declared in the global namespace, not in the std namespace. The first and second versions are implicitly declared in every translation unit of a C++ program: The header does not need to be included for them to be present. This seems to me to imply that the third version of operator new (placement new) is not implicitly declared in every translation unit of a C++ program and the header <new> does need to be included for it to be present. Is that correct? If so, how is it that using both g++ and MS VC++ Express compilers it seems I can compile code using the third version of new without #include <new> in my source code? Also, the MSDN Standard C++ Library reference entry on operator new gives some example code for the three forms of operator new which contains the #include <new> statement, however the example seems to compile and run just the same for me without this include? // new_op_new.cpp // compile with: /EHsc #include<new> #include<iostream> using namespace std; class MyClass { public: MyClass( ) { cout << "Construction MyClass." << this << endl; }; ~MyClass( ) { imember = 0; cout << "Destructing MyClass." << this << endl; }; int imember; }; int main( ) { // The first form of new delete MyClass* fPtr = new MyClass; delete fPtr; // The second form of new delete char x[sizeof( MyClass )]; MyClass* fPtr2 = new( &x[0] ) MyClass; fPtr2 -> ~MyClass(); cout << "The address of x[0] is : " << ( void* )&x[0] << endl; // The third form of new delete MyClass* fPtr3 = new( nothrow ) MyClass; delete fPtr3; } Could anyone shed some light on this and when and why you might need to #include <new> - maybe some example code that will not compile without #include <new> ? Thanks.

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  • trying to make a simple grid-class, non-lvalue in assignment

    - by Tyrfing
    I'm implementing a simple C++ grid class. One Function it should support is accessed through round brackets, so that I can access the elements by writing mygrid(0,0). I overloaded the () operator and i am getting the error message: "non-lvalue in assignment". what I want to be able to do: //main cGrid<cA*> grid(5, 5); grid(0,0) = new cA(); excerpt of my implementation of the grid class: template class cGrid { private: T* data; int mWidth; int mHeight; public: cGrid(int width, int height) : mWidth(width), mHeight(height) { data = new T[width*height]; } ~cGrid() { delete data; } T operator ()(int x, int y) { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } const T &operator ()(int x, int y) const { if (x >= 0 && x <= mWidth) { if (y >= 0 && y <= mHeight) { return data[x + y * mWidth]; } } } The rest of the code deals with the implementation of an iterator and should not be releveant.

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  • Why does this cast to Base class in virtual function give a segmentation fault?

    - by dehmann
    I want to print out a derived class using the operator<<. When I print the derived class, I want to first print its base and then its own content. But I ran into some trouble (see segfault below): class Base { public: friend std::ostream& operator<<(std::ostream&, const Base&); virtual void Print(std::ostream& out) const { out << "BASE!"; } }; std::ostream& operator<<(std::ostream& out, const Base& b) { b.Print(out); return out; } class Derived : public Base { public: virtual void Print(std::ostream& out) const { out << "My base: "; //((const Base*)this)->Print(out); // infinite, calls this fct recursively //((Base*)this)->Print(out); // segfault (from infinite loop?) ((Base)*this).Print(out); // OK out << " ... and myself."; } }; int main(int argc, char** argv){ Derived d; std::cout << d; return 0; } Why can't I cast in one of these ways? ((const Base*)this)->Print(out); // infinite, calls this fct recursively ((Base*)this)->Print(out); // segfault (from infinite loop?)

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  • What am i doing wrong

    - by Erik Sapir
    I have the following code. I need B class to have a min priority queue of AToTime objects. AToTime have operator, and yet i receive error telling me than there is no operator matching the operands... #include <queue> #include <functional> using namespace std; class B{ //public functions public: B(); virtual ~B(); //private members private: log4cxx::LoggerPtr m_logger; class AToTime { //public functions public: AToTime(const ACE_Time_Value& time, const APtr a) : m_time(time), m_a(a){} bool operator >(const AToTime& other) { return m_time > other.m_time; } //public members - no point using any private members here public: ACE_Time_Value m_time; APtr m_a; }; priority_queue<AToTime, vector<AToTime>, greater<AToTime> > m_myMinHeap; };

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  • How `is_base_of` works?

    - by Alexey Malistov
    Why the following code works? typedef char (&yes)[1]; typedef char (&no)[2]; template <typename B, typename D> struct Host { operator B*() const; operator D*(); }; template <typename B, typename D> struct is_base_of { template <typename T> static yes check(D*, T); static no check(B*, int); static const bool value = sizeof(check(Host<B,D>(), int())) == sizeof(yes); }; //Test sample class Base {}; class Derived : private Base {}; //Exspression is true. int test[is_base_of<Base,Derived>::value && !is_base_of<Derived,Base>::value]; Note that B is private base. Note that operator B*() is const. How does this work? Why this works? Why static yes check(D*, T); is better than static yes check(B*, int); ?

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