C++ std::string to char for using with OpenGL LoadBMP - c++

Question

I've got an string array
string name[1000];
and with
int counter;
counter = 0;
while(FindNextFile(fHandle, &wf))
{
... //some more code which is checking if its a folder
string theName = wf.cFileName;
if(theName.find(".bmp") != std::string::npos)
{
name[counter] = theName;
counter++;
}
}
I am adding each .bmp file to my name array.
Using NeHe's Tutorial I'm adding Textures to my Qubes, which is working very well.
Now my customized code looks like this:
int n; string imageFileString[1000]; char *imageFile[1000];
for(n=0; n<1000; n++)
{
imageFileString[n] = name[n];
imageFile[n] = new char[imageFileString[n].length()];
strcpy(imageFile[n], imageFileString[n].c_str());
if(TextureImage[n] = loadBMP(imageFile[n]))
{
... // Some more Functions to set textures
}
}
Everything is working well, only that my BMP Files arent loaded.
If I add
name[0] = "pic1.bmp";
name[1] = "pic2.bmp";
name[2] = "pic2.bmp";
name[3] = "pic2.bmp";
before setting the int n; string imageFileString..., so for the for(...) loop my Pictures are loaded without changing anything else. My first opinion was that the name array has no entrys, but I created a Log file with the output
name[0] << endl << name[1] << endl << name[2] ...
and in my Log file were the same names
pic1.bmp
pic2.bmp
pic3.bmp
so I think there is some other error adding the cFileName to my array.
Can anyone help me please? I dont know how to fix this, i mean I've no idea what is wrong...

Answer 1

imageFile[n] = new char[imageFileString[n].length()];
You're not accounting for the null-terminator. Add one to the length:
imageFile[n] = new char[imageFileString[n].length() + 1];

Answer 2

This isn't an answer, but it would be too hard to post in a comment.
Why are you doing all this?
int n; string imageFileString[1000]; char *imageFile[1000];
for(n=0; n<1000; n++)
{
imageFileString[n] = name[n];
imageFile[n] = new char[imageFileString[n].length()];
strcpy(imageFile[n], imageFileString[n].c_str());
if(TextureImage[n] = loadBMP(imageFile[n]))
{
... // Some more Functions to set textures
}
}
When you could just do this?
int n;
for(n=0; n<1000; n++)
{
if(TextureImage[n] = loadBMP(name[n].c_str()))
{
... // Some more Functions to set textures
}
}

Answer 3

Since you said everything works fine when you do name[0] = "pic1.bmp" etc, you need to print out/debug string theName = wf.cFileName; I would guess it is a pathing issue. wf.cFileName is probably returning a file path you aren't expecting.
For example I bet it's returning something like \MyData\Bitmaps\pic1.bmp where you are only expecting pic1.bmp
Update
Given all the other wonderful changes, you can also shorten it even further and do this
int counter = 0;
while (FindNextFile(fHandle, &wf))
{
if (strstr(wf.cFileName, ".bmp") != 0)
{
if(TextureImage[counter] = loadBMP(wf.cFileName)
{
... // Some more Functions to set textures
counter++
}
}
}
There isn't any reason to allocate more memory just to check if a string (".bmp") is present. Also note I don't update the counter unless the load succeeds.
You really should switch TextureImage to a std::vector then you wouldnt have to do any counting. Check to see if you pass wf.cFileName directly to your loadBMP if things work. And I do realize that this could present in an overflow due to TextureImage[] and counter which is why I suggest switching to std::vector. We don't see how he allocates TextureImage[], if it's like everything else it was with a magic number of 1000.
Also keep in mind that .cFileName is defined as TCHAR[] which can hold unicode values.

Answer 4

Ok I found the Problem myself,
Update, fixed version (WinMain):
void ScanTheDirectory()
{
// this function is scanning the directory and is adding
// each bmp file to the string array "name"
}
int initGL()
{
// this function calls the loadTextures() function
}
int loadTextures()
{
// this function is loading all files of the string array "name"
// converts them to a const char * and is adding them to the "textures" GLuint (array)
}
int WINAPI WinMain()
{
// this function is the main window which is showing the
// qubes (GL_QUBES)
ScanTheDirectory();
initGL();
}
The Problem was in WinMain(), because it looked like this:
initGL();
ScanTheDirectory();
If it is first calling the initGL(), so it is creating the Textures, and because the name array is empty, there are no Textures added to my Textures array.
After changing this to
ScanTheDirectory();
initGL();
Now it is first calling the ScanTheDirectory() void and so my name array is filled with names of BMP Image Files.
Now it can call the initGL and this is creating the Textures out of my Images.
Thanks for the Help, now my Code is looking a little bit clearer :D
Ahmet