C++ Delete Objects of dynamic Array

问题

I am programming with the C++ Builder from Embarcadero.I created an TImage Array :

TImage *Image[c] ; // c is 5 

after that I am creating dynamic Images on an BUTTON CLICK :

for (int i = 0; i < c; i++) 
    {

    Image[i] = new TImage(this); 
    Image[i]->Parent = BoardItem ; // BoardItem is an Item of an TabControl    
    Image[i]->Height = 20 ;        
    Image[i]->Width = 20 ;        
    Image[i]->Position->X = d ;   // d and e are defined in the public var's.
    Image[i]->Position->Y = e ;
    Image[i]->Bitmap = Icon->Bitmap ; // Icon is an Image on my Formular
}

It's working fine but the Icon->Bitmap is from a Database , which is also working fine . But on an second Button Click the old Images are not deleted. So everytime when I'm clicking the button again, the program is creating 5 more Images but the old ones are still there.

My question is now, how to refresh the old Images ? Should i delete the old Images an create then the new Images ? ( I tried this with ( delete , Free () , delete[] Array, but im always getting a violence ERROR ) Or should i refresh the old Images, in case there are Updates on the Bitmaps of the Images in the Database, and how ?

回答1:

You need two things:

Make sure that the pointers are initialized to null the first time around:
```
TImage* Image[c] = {};
```

Delete the old image when you load a new one:

delete Image[i];
Image[i] = new TImage(this);

Note that using delete on a null pointer is perfectly safe; it just doesn't do anything. So nothing changes on the first set of images, and each subsequent set automatically clears out the old ones instead of leaking.

回答2:

@Ben Voigt here you got my whole Code hope you can understand it . Everytime i want to click the button the old images should be refreshed. To do that i want to delete the old an after that crate the new ones .

TImage *Image[20]= {} ;

for (int i = 0; i < c; i++) 
{
str = " Hallo "

Image[i] = new TImage(this);  
Image[i]->Parent = BoardItem ;  
Image[i]->Height = 20 ;  
Image[i]->Width = 20 ;   
Image[i]->Position->X = d ;  
Image[i]->Position->Y = e ; 
Image[i]->Bitmap = Icon->Bitmap ;  
Image[i]->StyleName = str ;     
Image[i]->OnClick = ImageClick ;
d = d + 20 ;   // the next Image should be x-Position +20

if (d == 367) {  // 367 is the Width of my Formular  
  d = 7 ;       // If it is 367 Position-x is 7 again und Position-y is +20 
  e = e + 20 ;   
 }
}

来源：https://stackoverflow.com/questions/34665307/c-delete-objects-of-dynamic-array

标签

c++

arrays

image

dynamic

bitmap