You said "Sure it is. A Yacht is a Boat, and a Benz is a Car, and they are all Vehicles. However, until one of those objects actually exist, there are no instances". Going by that logic, why not derive whirlybird from Helicopter? whirlybird is a helicopter, after all. Then DavidCrow, SenthilKumar, instead of being instances of Humans, would be subclasses of Humans... DavidCrow wrote: By definition, an instance of class is the actual occurrence of that class. I agree and that's why I don't think Benz should be derived from Car. Regards Senthil _____________________________ My Blog | My Articles | WinMacro

Ok i will, thanks for the help guys much appreciated. Thanks. Education begins a gentleman, conversation completes him ;)

A Class is just a structure. Can youm write a structure with all these elements? "Naked we come and bruised we go." - James Douglas Morrison Best Wishes, ez_way

#include <ofstream> void LogMessage (LPCTSTR strMessage) { std::ostream OutputFile("C:\\MyFolder\\My_log_file.txt"); CTime CurrentTime = CTime::GetCurrentTime(); CString TimeMrk = "[" + CurrentTime.Format("%H:%M:%S") + "] "; OutputFile << TimeMrk << strMessage; //Logging the message into the file, with the format (for example) : "\[18:12:34\] Message to log..." } TOXCCT >>> GEII power

If your prototype for register_person is as you stated "register_person(person & registered", then all you really need to do is do "registered.push_back(®istered)". If you are uncertain of the number of persons, you should be going to the heap for allocation. Then you should be doing "news" on the Person objects and thus your prototype for register_person should be "register_person(person * registered)". You would then just need to do "registered.push_back(person)".

#include #include using namespace std; void CalculateValues(const int &a, double *b, double &c) //c only can be double,if float,then *b=c/d how to transfer from float to double {c=5; double d = 20.4;//only double. if(a == 0) { //*a += 1;//error c = a + d; } else { *b = c / d; c =a - *b +d; cout<<"a="<

It's been a while since I did homework. Here are some hints for my version. Each object should encapsulate the data about the instance of the object. For a book, this would be title, author, isbn etc. You'd probably want a unique book id too, since a library may have multiple copies of popular books. For a loan, you want to record the book, the customer, and the start/return dates. If you want history you have to save these after books are returned. A library is really a collection of other objects. You need some way for objects to persist. A librarian wouldn't type in the names of all the borrowers every day at system startup, or all the books. Steve S

bhangie wrote: ...a function prototype that does a deep copy I've never seen the adjective "deep" used with "copy." What does it mean? bhangie wrote: What is the deference between operator=() and Copy()? Fundamentally, nothing. It's all a matter of how you want to use it. Which of these looks more natural: Object a, b; a.Copy(b); // or a = b; "The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

hi man, in fact, we uns pointers for many reasons. First, in C++, the existence of the pointers comes from the compatibility with the C, in which references don't exist. We also use pointers instead of value copies in function calls because it become heavy and "memory hungry" if we transfer some big data structures... for that reason, we also have the const keyword to avoid writing on pointed datas. The last reason i see wee use pointers for, it is because sometimes, we don't use variable names to refer to datas (tables, vectors, queues...). We so don't have other way to manipulate these addresses that with pointers... TOXCCT alias Nicolas C.

could u please use a topic that describes the problem? Don't try it, just do it! ;-)

bhangie wrote: // Employee *NewEmp = new Emp ?? I assume you meant Employee *NewEmp = new Emp**loyee**? bhangie wrote: I want the new employees details in a file .dat it keeps on creating one employee overriding the previous info. So do you have something akin to: for each employee in list { open .dat file write employee info to file close .dat file } In other words, after writing all employees to the .dat file, what one employee is in the file: the first one in the list or the last? bhangie wrote: Am i using new wrong? or am i missing the hole new concept totaly You are using it correctly. However, at this point, there is no way to know if your design is sound. Five birds are sitting on a fence. Three of them decide to fly off. How many are left?

bhangie wrote: what a shallow copy does The copy is shallow when only the pointer is copied: void ShallowCopy(int* a) { int* b; b = a; } The copy is deep when the value at which the pointer points is copied: void DeepCopy(int* a) { int* b; *b = *a; } bhangie wrote: is it good or bad to use Depends on the situation. If a shallow copy is deleted, the original pointer no longer points to the expected data, which of course can be disasterous. That's one reason to implement copy constructors in C++, to ensure member pointers are copied correctly. -- Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so. (Douglas Adams)

Code Project is choke full of code, both snippets and full programs. Five birds are sitting on a fence. Three of them decide to fly off. How many are left?

Just as an excercise - Here is how to use iterators for the display: #include "stdafx.h" #include "vector" #include "iostream" #include "string" int _tmain(int argc, _TCHAR* argv[]) { std::vector< double > v(10); for(int i = 0; i < 10; ++i) v.push\_back(i + 0.1); //Display std::vector< double >::iterator it = v.begin(); while (it != v.end()) { std::cout << \*it << "\\n"; ++it; } std::string s; std::cin >> s; } Who is 'General Failure'? And why is he reading my harddisk?!?

Some comments: If you don't want a to change a variable, don't pass a reference to it. You can do something like this: void Calculate( const int a, int c, float* f ); Here I'm not passing any references and you cannot change 'a' within Calculate. I can change the value of 'c' within the function, except the variable will retain its original value upon return. Now you maybe asking why I changed the parameter order. Mainly preferrence. I like to have the same types grouped together. Yes, you can initialize 'a' just like you did with float. The variable 'a' at the point you placed it is not a constant value. If you have anymore questions, just ask. Larry J. Siddens Cornerstone Communications TAME THE DOCUMENT MONSTER www.unifier.biz