How to delete item from list, while iterating through list?

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  1. #1
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    How to delete item from list, while iterating through list?

    How would i delete an item from a list<> class while im iterating through the list? I need it to first delete the item, than go to the next item without any problems.

    Code:
    for(list<ThrowObject>::iterator it = throwObjects.begin(); it != throwObjects.end(); ++it)
    {
        ThrowObject& throwObject = *it;
    
        //do stuff
    
        if(****)  //delete the item
        {
          ??
        }
    }

  2. #2
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by 39ster View Post
    How would i delete an item from a list<> class while im iterating through the list? I need it to first delete the item, than go to the next item without any problems.
    You have to obtain the next iterator value BEFORE erasing the element the iterator is pointing to. Generally:

    Code:
    for(iterator it = x.begin(), next; it != x.end(); it = next)
    {
        next = it;
        ++next;
        // do stuff, possibly deleting the element
    }

  3. #3
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    Worked. Thanks.

  4. #4
    Confused Magos's Avatar
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    The "erase" method returns the next iterator when removing:
    Code:
    std::list<T>::iterator i = List.begin();
    while(i != List.end())
    {
      if(ShouldIDeleteThis())
      {
        i = List.erase(i);
      }
      else
      {
        i++;
      }
    }
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  5. #5
    The larch
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    You can also avoid the manual loop if you turn the if (...) contents into a unary function/function object and use list::remove_if
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

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