Should you use the this pointer in the constructor?
Constructors, C++ FAQ LiteSome people feel you should not use the this pointer in a constructor because the object is not fully formed yet. However you can use this in the constructor (in the {body} and even in the initialization list) if you are careful. Here is something that always works: the {body} of a constructor (or a function called from the constructor) can reliably access the data members declared in a base class and/or the data members declared in the constructor's own class.
Related QuestionsWhat is the proper use of a laser pointer?
FDA Radiological Health Program - Frequently Asked Questions...Remember, laser pointers are not toys and they should only be used by an adult, or with adult supervision. the class designation, ranging from Class I to IIIa. Class IIIb and IV products should be used only by individuals with proper training and in applications where there is a legitimate need for these high-powered products.
Related QuestionsWhy won't my servlet compile? Q: Can I use a constructor in my servlet?
Code Style: Java servlets frequently asked questions (FAQ)A servlet is a normal Java class, so when there are no custom constructors, there is an implicit default constructor with no arguments. Servlet containers typically use the Class.newInstance() method to load servlets, so you must be careful to add an explicit default constructor if you add non-default constructors.
Related QuestionsCan I use a constructor in my servlet? Q: Can I use a normal class to handle my requests?
Code Style: Java servlets frequently asked questions (FAQ)Servlets are normal Java classes, they compile and run just like any other class. All that is required is that servlets implement the javax.servlet.Servlet interface. Usually, they extend a protocol-specific class such as javax.servlet.http.HttpServlet.
Related QuestionsWhat is a constructor?
snitfaq - Snit's Not Incr Tcl, OO systemIn object-oriented programming, an object's constructor is responsible for initializing the object completely at creation time. The constructor receives the list of options passed to the snit::type command's create method and can then do whatever it likes. That might include computing instance variable values, reading data from files, creating other objects, updating type and instance variables, and so forth.
Related QuestionsHow do I call the constructor?
FAQThe Polynomial(int d, double *coefs) constructor is invoked when an object of type Polynomial is defined using the appropriate arguments. For example, double co[] = { 1.2, 3.4, 5.6 }; Polynomial p(2, co); constructs p to represent 5.6x2 + 3.4 x + 1.2.
Related QuestionsWhy I deleted a pointer, then use it, I still get the same data?
FAQ on C/C++/Unix by Roseanne Zhang, Java Programmer Certifi...Yes, sometimes, it still can be used to get the same value, sometimes it does not. Sometimes, you will get a segmentation error. The language does not check the validity of the pointer. The programmer is responsible to use the pointers responsiblely. That is one problem of c/c++, which are not a safe language, but it is highly efficient! The following sample program will demonstrate the concepts.
Related QuestionsCan I use a reference to a pointer?
FAQs | DevelopersVoice.comReferences to pointers can be declared in much the same way as references to objects. Declaring a reference to a pointer yields a modifiable value that is used like a normal pointer. The following example illustrates the difference between using a pointer and a reference, and the difference between using a pointer to a pointer and a reference to a pointer.
Related QuestionsWhat is a far pointer? where we use it?
OOPS FAQ - Page 6Latest Answer: near, far pointers are the types of pointers in C. By using these pointers we can directly access me...
Related QuestionsWhat Is A Pointer?
Windows BasicsA pointer is the arrow you use to choose things on screen. Since the Shortcut is simply a pointer to a specific program or file, you can delete the shortcut or remove it from the Desktop without actually deleting the program or file.
Related QuestionsOOPS FAQ - Page 19Latest Answer: pointer : pointer is a derived data type which holds addresses as its value. it points to value at i...Related Questions
Code Style: Java objects frequently asked questions (FAQ)Use the form below to submit a help request or general enquiry about the Code Style Web site. Before you write read the guidelines on asking the right questions, and check this page for periodic updates. Your email address will not be mis-used. If you include your address you may be sent a personal reply, you will not be added to any mailing list unless you request it. Read the site privacy statement for details.Related Questions
What is a smart pointer and should I use it?
DirectX Frequently Asked QuestionsA smart pointer is a C++ template class designed to encapsulate pointer functionality. In particular, there are standard smart pointer classes designed to encapsulate COM interface pointers. These pointers automatically perform QueryInterface instead of a cast and they handle AddRef and Release for you. Whether you should use them is largely a matter of taste.
Related QuestionsWhy do we need a constructor in a servlet if we use the init method?
jGuru: Servlets FAQ Home PageEven though there is an init method in a servlet which gets called to initialise it, a constructor is still required to instantiate the servlet. Even...
Related QuestionsFAQ125 - How can I use 'Create' as a property instead of a constructor?
RemObjects Software: Developer Center: FAQThere is a problem with the following code: var Mode: System.IO.FileMode; begin Mode := System.IO.FileMode.Create; end; The Chrome compiler will consider 'Create' to be a constructor rather than a property. The...
Related QuestionsCan we use the constructor, instead of init(), to initialize servlet?
AKAAS :: JSP Interview Questions and Answers | JSP Frequentl...Yes , of course you can use the constructor instead of init(). There’s nothing to stop you. But you shouldn’t. The original reason for init() was that ancient versions of Java couldn’t dynamically invoke constructors with arguments, so there was no way to give the constructur a ServletConfig. That no longer applies, but servlet containers still will only call your no-arg constructor. So you won’t have access to a ServletConfig or ServletContext.
Related QuestionsIs a null statement a null pointer?
Infrequently Asked Questions in comp.lang.cNo. A null pointer is a pointer where all of the address bits are zero (no matter what the segment bits are), and can be obtained by typing '(char *) (int) 0'. A null statement is not a pointer to anything. They are not interchangeable, although you can combine them to get an effectively-null statement, such as NULL;. This does not buy you anything. [a] Send large donations, checks, and money orders to the author of the FAQ, or the moderator of the group, whichever you prefer.
Related QuestionsWhat is a type constructor?
snitfaq - Snit's Not Incr Tcl, OO systemA type constructor is a body of code that initializes the type as a whole, rather like a C++ static initializer. The body of a type constructor is executed once when the type is defined, and never again.
Related QuestionsHow do I define a constructor?
snitfaq - Snit's Not Incr Tcl, OO systemA constructor is defined by using the constructor statement in the type definition. Suppose that it's desired to keep a list of all pedigreed dogs. The list can be maintained in a type variable and retrieved by a type method. Whenever a dog is created, it can add itself to the list--provided that it's registered with the American Kennel Club.
Related QuestionsCan constructor be overridden?
JavaChina, SCJP Questions and Answers by Roseanne Zhang (2)Can you explain the result of the following example? Oh, my! class Base { public boolean foo(Base b) { return true; } } class Sub extends Base { public boolean foo(Sub s) { return false; } } public class Test { public static void main(String argv[]) { Base bb = new Base(); Base bs = new Sub(); Sub ss = new Sub(); System.out.println(bb.foo(bb)); //true System.out.println(bs.foo(bs)); //true ??? System.out.println(bs.foo(ss)); //true ??? System.out.println(bs.foo(bb)); //true ??? System.out.
Related QuestionsCan I use static object instead of static pointer inside the singleton definition?
FAQ on C/C++/Unix by Roseanne ZhangThis code is actually the same as GoF's book. The singleton pattern is from many many programmers' industrial practice. Don't change it unless you are abosolute sure what you are doing. Just think a scenario, you have several huge different singletons using 2M or more memory each, and they are only needed in ~5 minutes once or once a day, however, your program is going to run 5 years continuously by 24*7.
Related QuestionsCan I use a pointer to class/struct Node as a data member in the above question?
FAQ on C/C++/Unix by Roseanne Zhang, Java Programmer Certifi...It is the programmer's responsibility to make sure your recursion code have a exit point!!! See the following code (borrowed from above question), no compiling errors, no linking errors, but the program will never print out the "after". struct Node { int num; Node *next; Node() { next = new Node(); //Infinite recursion!!! } }; int main() { printf("before\n"); Node a; //run out of memory, soon be dead! printf("after\n"); }
Related QuestionsHow unsafe is it to use (assign, compare) a pointer value after it's been freed?
Memory AllocationWhen you call free, the memory pointed to by the passed pointer is freed, but the value of the pointer in the caller probably remains unchanged, because C's pass-by-value semantics mean that called functions never permanently change the values of their arguments. (See also question 4.8.) A pointer value which has been freed is, strictly speaking, invalid, and any use of it, even if it is not dereferenced (i.e.
Related QuestionsIf NULL and 0 are equivalent as null pointer constants, which should I use?
Null PointersMany programmers believe that NULL should be used in all pointer contexts, as a reminder that the value is to be thought of as a pointer. Others feel that the confusion surrounding NULL and 0 is only compounded by hiding 0 behind a macro, and prefer to use unadorned 0 instead. There is no one right answer. (See also questions 9.4 and 17.10.) C programmers must understand that NULL and 0 are interchangeable in pointer contexts, and that an uncast 0 is perfectly acceptable.
Related QuestionsHow do I create and use an array of pointer-to-member-function?
Pointers to member functions, C++ FAQ LiteNote: #define macros are evil in 4 different ways: evil#1, evil#2, evil#3, and evil#4. But they're still useful sometimes. Feel ashamed, feel guilty, but when an evil construct like a macro improves your software, use it.
Related QuestionsWhy doesn't the construct-on-first-use idiom use a static object instead of a static pointer?
Constructors, C++ FAQ LiteShort answer: it's possible to use a static object rather than a static pointer, but doing so opens up another (equally subtle, equally nasty) problem. Long answer: sometimes people worry about the fact that the previous solution "leaks." In many cases, this is not a problem, but it is a problem in some cases.
Related Questionswhat is a NULL Pointer? Whether it is same as an uninitialized pointer?
OOPS FAQ - Page 7Latest Answer: NULL pointer is pointer which is not pointing to anything in the memory. NULL is defined as (v...
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