using IEnumerator to removing items

I want to remove some items from an ArrayList. Can I do that using a foreach(…)- loop an IEnumerator like this.

foreach(string s in arraylist)

{

if (s == “del”)

{

// Here I want to remove the item from arraylist…

}

Any ideas how to solve this without creating a new ArrayList and add items I want to save. Feels like that solution will bee to time consuming…

All tips are welcomed!.

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using IEnumerator to removing items

Pete0511

You can't do this with an enumerator because when you change the collection while enumerating an exception is thrown.

To solve this problem use a for-loop, or a while with index of. Here are the two examples:

For-loop

for( int i = 0; i < arraylist.Count; i++ )
{
    string currentValue = (string)arraylist[ i ];

    if( currentValue.Equals( "del" ) )
    {
        // TODO: Do delete logic here.

        // Lower the current index value
        // because a other value will be
        // available on that index.
        i--;
    }
}

While-loop

int index = 0;

while( (index = arraylist.IndexOf( "del" )) != -1 )
{
arraylist.RemoteAt( index );
}

wirol
Indeed, you can't use a foreach to delete items in a collection, since the collection will change.
However, this for-loop that P.J. Van de Sande posts can be written better like this:

for( int i = arrayList.Count - 1; i >= 0; i -- )
{
   if( arrayList[ i ].ToString == "del" )
   {
         arrayList.RemoveAt( i );
   }
}
Seraph Jiang
Indeed, good notice Frederik! Now when you remove at item at the index it won't effect the other items because you remove the item from the end.
using IEnumerator to removing items

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using IEnumerator to removing items

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using IEnumerator to removing items

using IEnumerator to removing items

Pete0511

wirol

Seraph Jiang