Question

Dynamic Array at run time

Asked by: TopKah

Hello,
Im using C++ builder 2009  to open  text file with (TStreamReader) and read the file line by line to extract the delimited text  and store it in a string array.
I want to be able to store these extracted text in 2d array, and expand the size of array dynamically according to how many lines I have in the text .

i try to use String**myArray  but with no succeed

TStreamReader* myST = new TStreamReader(FileName);
	TSysCharSet splitChars1 = TSysCharSet() << ';';
	int i = 0;
	String**myArray;
	while (myST->EndOfStream == false)
	{
		UnicodeString Buffer = myST->ReadLine();
		TStringList* St = new TStringList();
		int j = ExtractStrings(splitChars1, splitChars1, Buffer.w_str(), St);
		i++;
		for (int y = 0; y < i ; j++) {
			myArray[y]=new String[i];
		}
 
		for (int k = 0; k < St->Count; k++) {
			myArray[i][k]=St->Strings[k];
		}
	}
	myST->Free();

                                  
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Asked On
2009-10-22 at 04:48:37ID24834054
Tags

c++

,

C++ builder

Topics

C++ Builder

,

C++ Programming Language

,

Microsoft Visual C++

Participating Experts
3
Points
500
Comments
10

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Answers

 

by: QlemoPosted on 2009-10-22 at 18:05:50ID: 25640604

I'm not using C++ Builder, but at the first glance, with C++ knowledge, I see that you are not allocating memory for the array. You are declaring a   **String, that only allocates a pointer structure for vectors, not for the vectors themselves. All dimensions are undefined, but you need to define the first dimension of the 2-dimensional array (or pointer on vectors). Please review what a **String really means ...

 

by: evilrixPosted on 2009-10-23 at 02:01:39ID: 25642458

Well, this is pretty simple to do using standard C++ ifstream, vector, string and getline. I can show you how if you like but I see you are using Borland specific classes so I don't want to give you a solution that is not suitable.

 

by: TopKahPosted on 2009-10-23 at 02:31:38ID: 25642638

thanks all , i solve it using vector and stringlist like this :


TStreamReader* myST = new TStreamReader(FileName);
        TSysCharSet splitChars1 = TSysCharSet() << ';';
        int i = 0;
        vector<TStringList*>myArray;
        while (myST->EndOfStream == false)
        {
                UnicodeString Buffer = myST->ReadLine();
                TStringList* St = new TStringList();
                int j = ExtractStrings(splitChars1, splitChars1, Buffer.w_str(), St);
                i++;
                 myArray.push_back(St);
        }
        myST->Free();
 
for (int i = 0; i < myArray.size(); i++)
        {
               for (int x = 0; x < myArray[i]->Count; x++)
            {
                String s = myArray[i]->Strings[x];
            }
         
        }

                                              
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by: evilrixPosted on 2009-10-23 at 02:34:56ID: 25642653

>>  i solve it using vector and stringlist like this :

Which is what I suggested here {http:#25642458}

"Well, this is pretty simple to do using standard C++ ifstream, vector, string and getline."

 

by: evilrixPosted on 2009-10-23 at 02:37:39ID: 25642667

BTW: Why create these on the heap (thus making the extra work of having to delete everything and runt he risk of memory leak). Why not copy TStringList into the vector by value?

 

by: pgnatyukPosted on 2009-10-23 at 02:47:10ID: 25642723

or why not TList?
http://www.functionx.com/bcb/classes/tlist.htm

Here is an example:

http://bcbjournal.org/articles/vol2/9807/Sorting_a_TList.htm?PHPSESSID=a6f7080822783243af81a8fc7d4b46d4

I cannot say I remember C++ Builder very well, it does support the standard library, but I cannot say that it looks very natural for C++ Builder code.

 

by: pgnatyukPosted on 2009-10-23 at 03:01:19ID: 25642785

Maybe, evilrix is right. :)
I checked the C++ builder code (with DynamicArray and TStringList). Samples with vector looks much better.
http://www.functionx.com/bcb/articles/dynarray.htm

http://www.programmersheaven.com/mb/bcbuilder/369007/369007/dynamic-array/

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