Error Definition Of Implicitly-declared Irtual
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Error Definition Of Implicitly Declared Copy Constructor
Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes error definition of implicitly declared default constructor a minute: Sign up Can anyone help me understand this error? “definition of implicitly-declared ‘classA::classA()’” up vote 20 down vote favorite 1 Heres the code: #include
Definition Of Implicitly Declared Copy Assignment Operator
it): class classA { public: classA(); // you forgot this! protected: void setX(int a); private: int p; }; Now you can write its definition outside the class which you've already done. share|improve this answer edited Apr 23 '11 at 17:41 answered Apr 23 '11 at 17:36 Nawaz 203k62447654 Actually, the thing which I know was that the default constructor is provided by the compiler by default. Here you have mentioned that definition of the constructor was missing. But, I was not knowing the 'WHY' we have to provide the default constructor when it is already being provided by the compiler. But, now, I knew that if we are defining the default constructor which is not in accordance with the one provided by the compiler, we will have to define it explicitly. I din't find the 'WHY'. :) –Chaitanya Mar 6 '13 at 9:43 @Chaitanya: The compiler does generate a default constructor for you IF you don't declare (and define) one yourself. In the question, the OP has attempted to define the default constructor outside the class, without declaring it in the class. The code is ill-formed, and the compiler would generate error. Let me know if you understand it now (see the code in the question to completely understand it). –Nawaz Mar 6 '13 at 11:01 I got the point now. So, its like once we define a default constructor, thats got to be declared. O
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Which Is Of Non-class Type
Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up c++ compiling error related to constructor/destructor http://stackoverflow.com/questions/5765780/can-anyone-help-me-understand-this-error-definition-of-implicitly-declared-cl definition up vote 16 down vote favorite 4 I'm trying to define the constructor and destructor of my class but I keep getting the error: definition of implicitly-declared 'x::x()' What does it mean? Part of the code: ///Constructor StackInt::StackInt(){ t = (-1); stackArray = new int[20]; }; ///Destructor StackInt::~StackInt(){ delete[] stackArray; } c++ constructor destructor share|improve this question edited Mar 1 '13 at 15:48 Drew Noakes http://stackoverflow.com/questions/708008/c-compiling-error-related-to-constructor-destructor-definition 127k73394489 asked Apr 2 '09 at 1:53 caesar 1 Post your code ! –Uri Apr 2 '09 at 1:54 How are your files structured (*.h, *.cpp)? Which file is that posted code in? –paxdiablo Apr 2 '09 at 2:02 add a comment| 2 Answers 2 active oldest votes up vote 40 down vote In the class declaration (probably in a header file) you need to have something that looks like: class StackInt { public: StackInt(); ~StackInt(); } To let the compiler know you don't want the default compiler-generated versions (since you're providing them). There will probably be more to the declaration than that, but you'll need at least those - and this will get you started. You can see this by using the very simple: class X { public: X(); // <- remove this. }; X::X() {}; int main (void) { X x ; return 0; } Compile that and it works. Then remove the line with the comment marker and compile again. You'll see your problems appear then: class X {}; X::X() {}; int main (void) { X x ; return 0; }
qq.cpp:2: error: definition of implicitly-declared `X::X()'sh
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or http://stackoverflow.com/questions/8563116/destructor-of-a-class-implicitly-defined posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Destructor of a class implicitly defined up vote 1 down vote favorite 1 Consider the case of class which does not have a destructor and constructor explicitly declared by the developer. I understand that a destructor definition of for a class will be implicitly declared in this case. Then is it true that the destructor is implicitly defined, only when an object of the class is about to be destroyed? Is the behavior of constructor also the same as above. Is it implicitly defined only when an object of the class is created? EDIT class A { public: }; int main() { } In the above code, ~A() will be implicitly declared. My question is whether it true that definition of implicitly the definition for the destructor will be made implicitly, only if an object of the class is instantiated like class A { public: }; int main() { A a; } Or is it implicitly defined, even if object instantiation is not done ? c++ constructor destructor explicit-constructor share|improve this question edited Dec 19 '11 at 15:12 asked Dec 19 '11 at 14:57 nitin_cherian 2,130134388 Maybe we can give better answers if you explain why this is relevant. –Sebastian Mach Dec 19 '11 at 15:03 Are you making some sort of distinction between implicitly declared and implicitly defined? I am really struggling to understand the question... –NPE Dec 19 '11 at 15:05 I have added some code snippet for clarity. –nitin_cherian Dec 19 '11 at 15:13 @LinuxPenseur: What do you need this for? –Sebastian Mach Dec 19 '11 at 15:24 @phresnel : I am studying the basics of the C++ language. I want a concrete idea of what is happening. If ever someone asks me the question after i have mastered the language, i should be able to give the correct answer. –nitin_cherian Dec 19 '11 at 15:34 | show 1 more comment 3 Answers 3 active oldest votes up vote 4 down vote accepted Yes, implicitly declared default constructors and destructors are implicitly defined when they are used to create or destroy instances of the object. In the words of