store the string file into dynamic array

Question

I have three string file that will be stored into dynamic array, but I just try one of three file to test if this succed, so I'll do the same way to handle the three file i have. the goal i'll shown the string that I get from the file to a ListView this my code.

void __fastcall TFrmNewPeta::showDefaultRute() {
    std::string lineDataAwal;
    std::ifstream ifs_Awal;
    int tempIndexAwal = 0;
    ifs_Awal.open("DefaultDataAwal");

        /*counting the line*/
        while(std::getline(ifs_Awal,lineDataAwal)){++tempIndexAwal;}

        /*use dynamic array to stored string*/    
        std::string *s = new std::string[tempIndexAwal];

        for(int dx=0;dx<tempIndexAwal;dx++)
        {
            while(std::getline(ifs_Awal,lineDataAwal))
          s[dx] = lineDataAwal[dx++];
        }

        for(int dex =0;dex<tempIndexAwal;++dex)
        {
           ItemDefult = ListView1->Items->Add();
           ItemDefult->Caption = String(IntToStr(dex + 1));
           ItemDefult->SubItems->Add(s[dex].c_str());
        }
        ifs_Awal.close();
    delete []s;
    s = NULL;
}

there's no errors during compile, but the result ListView just showing the number with this code ItemDefult->Caption = String(IntToStr(dex + 1)); can anyone show me how the best way for i do.

Hello @chris thanks for you advice. I have try using 'std::vector' but I got the error, I'm using 'cpp builder 2010' this the code std::vector(std::string) myline; while(std::getline(ifs_Awal,myline)) { myline.push_back(myline); } — Bika Shad
– Bika Shad, Commented Oct 6, 2013 at 7:11
the error exactly where the line 'while' exist? compiller says "could not find a match for std::string <_Elem,_Traits,_Alloc>..." — Bika Shad
– Bika Shad, Commented Oct 6, 2013 at 7:20

Zac Howland · Accepted Answer · 2013-10-05 23:22:27Z

3

You are reading the file, leaving it open, and expecting to read it again. That won't work because the cursor in the file is at the end of the file (so your second while loop does nothing).

A much better approach would be:

std::vector<std::string> lines;
std::string line;
std::ifstream fin("Youfilename");

while (std::getline(fin, line))
{
    lines.push_back(line);
}
fin.close();
// add data to your list view

answered Oct 5, 2013 at 23:22

Zac Howland

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3 Comments

Bika Shad Over a year ago

hi @Zac Howland thanks for your suggestion, and I'm sorry I forgot to put delocator for showing on the post. so I was edit my code, please see the above. I have been try your code but I get the error the where "while" exist. the compiler says "could not find a match for std::string <_Elem,_Traits,_Alloc>..."

LorenzoDonati4Ukraine-OnStrike Over a year ago

Probably because @ZacHowland gave it for granted that you knew that you must #include <vector> and #include <string> in your source file before you can use his snippet. Did you include those header files?

Bika Shad Over a year ago

Hi @lorenzo Donati, yes i do first into header file. and I've to make a thread for the problems std::vector and i get correct answer. thanks for your advice

Adhy · Accepted Answer · 2013-10-06 14:32:53Z

1

its easier if you use std::vector for dynamic arrays and don't forget to first include the file header with #include<vector>

void __fastcall TFrmNewPeta::showDefaultRute() {
    std::string lineDataAwal;
    std::ifstream ifs_Awal;
    std::vector<std::string> vec;
    ifs_Awal.open("DefaultDataAwal");

   /*get the string of lineDataAwal */
    while(std::getline(ifs_Awal,lineDataAwal))
    { vec.push_back(lineDataAwal);}

    for(int dex =0;dex<vec.size();++dex) 
    {
      ItemDefult = ListView1->Items->Add();
      ItemDefult->Caption = String(IntToStr(dex + 1));
      ItemDefult->SubItems->Add(vec.at(dex).c_str()); 
    }
   ifs_Awal.close();
}

Hope this helps

answered Oct 6, 2013 at 14:32

Adhy

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1 Comment

Bika Shad Over a year ago

Hi @Adhy. Wow you back on my post and help me again. the code your as shown, that's exactly what I want. thank you very much

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