 |  |  |  |  |  |  |  |
vector trouble
Please support our C++ advertiser: Intel Parallel Studio Home
 |
If you make a vector of a class of no designated size, as you reserve spaces inside the vector will it just make a default instance from the constructor?
•
•
Join Date: Jul 2005
Posts: 1,678
Reputation: 
Solved Threads: 263
Probably, you can check it out pretty easy.
Be careful of the word size. size is frequently used to indicate the actual number of elements currently in the vector as opposed to the number of elements for which space is allocated for vector use, which might be called capacity or size.
Be careful of the word size. size is frequently used to indicate the actual number of elements currently in the vector as opposed to the number of elements for which space is allocated for vector use, which might be called capacity or size.
Klatu Barada Nikto
Fortunately you CAN'T invent a "class of no designated size" in C++. For every class its objects have fixed and defined size (remember operator sizeof).
If you mean a class with dynamically allocated members then it's a problem of this class constructor, not a vector container. That's why class constructors were invented.
If you mean a class with dynamically allocated members then it's a problem of this class constructor, not a vector container. That's why class constructors were invented.
i meant i created a vector of unspecified size. but when I reserve a spot then try to alter the instance an error pops up and I get a window telling me that the program has to close because it has run into an error. I just don't know what is going on.
•
•
Join Date: Nov 2008
Posts: 950
Reputation:
Solved Threads: 92
Posting Shark
Post code.
"Jedenfalls bin ich überzeugt, daß der Alte nicht würfelt."
"I became very sensitive to what will happen to all this and all of us." -Two geniuses named Albert
"I became very sensitive to what will happen to all this and all of us." -Two geniuses named Albert
•
•
Join Date: May 2008
Posts: 51
Reputation:
Solved Threads: 2
Junior Poster in Training
Your question is difficult to understand, but if you mean will it construct what you have in a default constructor to each instance of said class, then yes it should.
If you are using std::vector class then probable causes are:
1. You reserve vector size then try to access its elements, but reserve member function does not construct vector elements. You need resize (not reserve) vector if you want to access new elements immediatly.
2. Your class has bad default constructor (constructor without arguments). For example:
New Bad objects created after vector<Bad>::resize(k) are true bad. There are garbage values of pDynArr member in all 10 vector elements. The destructor of troubles calls Bad destructor for every 10 elements, the last one call delete [] pDynArr for undefined pointer.
Follow MosaicFuneral's advice
...
1. You reserve vector size then try to access its elements, but reserve member function does not construct vector elements. You need resize (not reserve) vector if you want to access new elements immediatly.
2. Your class has bad default constructor (constructor without arguments). For example:
C++ Syntax (Toggle Plain Text)
Follow MosaicFuneral's advice
... Last edited by ArkM; Nov 19th, 2008 at 2:13 am.
|
Similar Threads
- GUI, matrix and vector libraries (C++)
- help:stl vector of user defined objects (C)
- Trouble with Pointers and Arrays (C)
Other Threads in the C++ Forum
- Previous Thread: sub proceedure/function Qs
- Next Thread: Multi Client server
| Thread Tools | Search this Thread |
You need to join our community in order to build your list of favorite forums. You can visit the forum index for a listing of all forums.
Related Forum Features
Latest C++ Posts
- Today's Posts
- Unanswered Threads
api array based beginner binary c++ c/c++ calculator char char* class classes code compile compiler console conversion count delete deploy desktop directshow dll download dynamic dynamiccharacterarray encryption error file forms fstream function functions game givemetehcodez google graph gui homeworkhelp homeworkhelper iamthwee ifstream input int integer java lib linkedlist linker linux list loop looping loops map math matrix memory news numbertoword output parameter pointer problem program programming project proxy python random read recursion recursive reference return rpg sorting string strings struct temperature template templates test text text-file tree unix url variable vector video visual visualstudio win32 windows winsock word wordfrequency wxwidgets
