How do I loop through items in a list box and then remove those item

Question

I m getting the error below when trying to loop through a listbox and then remove the item      List that this enumerator is bound to has been modified  An enumerator can only be used if the list does not change    foreach  string s in listBox1 Items        MessageBox Show s         do stuff with  s       listBox1 Items Remove s       How can I remove the item and still loop through the contents

User · Answer

Here my solution without going backward and without a temporary list  while  listBox1 Items Count  gt  0      string s   listBox1 Items 0  as string       do something with s   listBox1 Items RemoveAt 0

User · Answer

How about   foreach var s in listBox1 Items ToArray          MessageBox Show s         do stuff with  s       listBox1 Items Remove s       The ToArray makes a copy of the list  so you don t need to worry about it changing the list while you are processing it

User · Answer

Everyone else has posted  going backwards  answer  so I ll give the alternative  create a list of items you want to remove  then remove them at the end   List lt string gt  removals   new List lt string gt     foreach  string s in listBox1 Items        MessageBox Show s         do stuff with  s       removals Add s      foreach  string s in removals        listBox1 Items Remove s       Sometimes the  work backwards  method is better  sometimes the above is better - particularly if you re dealing with a type which has a RemoveAll collection  method  Worth knowing both though

User · Answer

Jefferson is right  you have to do it backwards   Here s the c  equivalent   for  var i    list Items Count - 1  i  gt   0  i--        list Items RemoveAt i

User · Answer

You have to go through the collection from the last item to the first  this code is in vb  for i as integer  list items count-1 to 0 step -1      list items removeat i  next

User · Answer

Here my solution without going backward and without a temporary list  while  listBox1 Items Count  gt  0      string s   listBox1 Items 0  as string       do something with s   listBox1 Items RemoveAt 0

User · Answer

Jefferson is right  you have to do it backwards   Here s the c  equivalent   for  var i    list Items Count - 1  i  gt   0  i--        list Items RemoveAt i

User · Answer

Here my solution without going backward and without a temporary list  while  listBox1 Items Count  gt  0      string s   listBox1 Items 0  as string       do something with s   listBox1 Items RemoveAt 0

User · Answer

How about   foreach var s in listBox1 Items ToArray          MessageBox Show s         do stuff with  s       listBox1 Items Remove s       The ToArray makes a copy of the list  so you don t need to worry about it changing the list while you are processing it

User · Answer

Do you want to remove all items  If so  do the foreach first  then just  use Items Clear   to remove all of them afterwards   Otherwise  perhaps loop backwards by indexer   listBox1 BeginUpdate    try     for int i   listBox1 Items Count - 1  i  gt   0   i--           do with listBox1 Items i       listBox1 Items RemoveAt i         finally     listBox1 EndUpdate

User · Answer

Do you want to remove all items  If so  do the foreach first  then just  use Items Clear   to remove all of them afterwards   Otherwise  perhaps loop backwards by indexer   listBox1 BeginUpdate    try     for int i   listBox1 Items Count - 1  i  gt   0   i--           do with listBox1 Items i       listBox1 Items RemoveAt i         finally     listBox1 EndUpdate

User · Answer

Everyone else has posted  going backwards  answer  so I ll give the alternative  create a list of items you want to remove  then remove them at the end   List lt string gt  removals   new List lt string gt     foreach  string s in listBox1 Items        MessageBox Show s         do stuff with  s       removals Add s      foreach  string s in removals        listBox1 Items Remove s       Sometimes the  work backwards  method is better  sometimes the above is better - particularly if you re dealing with a type which has a RemoveAll collection  method  Worth knowing both though

User · Answer

How about   foreach var s in listBox1 Items ToArray          MessageBox Show s         do stuff with  s       listBox1 Items Remove s       The ToArray makes a copy of the list  so you don t need to worry about it changing the list while you are processing it

User · Answer

Do you want to remove all items  If so  do the foreach first  then just  use Items Clear   to remove all of them afterwards   Otherwise  perhaps loop backwards by indexer   listBox1 BeginUpdate    try     for int i   listBox1 Items Count - 1  i  gt   0   i--           do with listBox1 Items i       listBox1 Items RemoveAt i         finally     listBox1 EndUpdate

User · Answer

Here my solution without going backward and without a temporary list  while  listBox1 Items Count  gt  0      string s   listBox1 Items 0  as string       do something with s   listBox1 Items RemoveAt 0

User · Answer

How about   foreach var s in listBox1 Items ToArray          MessageBox Show s         do stuff with  s       listBox1 Items Remove s       The ToArray makes a copy of the list  so you don t need to worry about it changing the list while you are processing it

User · Answer

You have to go through the collection from the last item to the first  this code is in vb  for i as integer  list items count-1 to 0 step -1      list items removeat i  next

User · Answer

Do you want to remove all items  If so  do the foreach first  then just  use Items Clear   to remove all of them afterwards   Otherwise  perhaps loop backwards by indexer   listBox1 BeginUpdate    try     for int i   listBox1 Items Count - 1  i  gt   0   i--           do with listBox1 Items i       listBox1 Items RemoveAt i         finally     listBox1 EndUpdate

User · Answer

You can t make modification to the collection being iterated within the ForEach block   A quick fix is to iterate over a copy of the collection   An easy way to make this copy is through the ArrayList constructor   The DataRowView objects in the copied collection will refer to  and be able to modify  the same underlying data as your code   For Each item As DataRowView In New System Collections ArrayList lbOrdersNeedToBeVoided Items    please read http   social msdn microsoft com Forums en-AU vbgeneral thread b4d1f649-d78a-4e5b-8ad8-1940e3379bed

User · Answer

You can t make modification to the collection being iterated within the ForEach block   A quick fix is to iterate over a copy of the collection   An easy way to make this copy is through the ArrayList constructor   The DataRowView objects in the copied collection will refer to  and be able to modify  the same underlying data as your code   For Each item As DataRowView In New System Collections ArrayList lbOrdersNeedToBeVoided Items    please read http   social msdn microsoft com Forums en-AU vbgeneral thread b4d1f649-d78a-4e5b-8ad8-1940e3379bed

User · Answer

Everyone else has posted  going backwards  answer  so I ll give the alternative  create a list of items you want to remove  then remove them at the end   List lt string gt  removals   new List lt string gt     foreach  string s in listBox1 Items        MessageBox Show s         do stuff with  s       removals Add s      foreach  string s in removals        listBox1 Items Remove s       Sometimes the  work backwards  method is better  sometimes the above is better - particularly if you re dealing with a type which has a RemoveAll collection  method  Worth knowing both though

User · Answer

You have to go through the collection from the last item to the first  this code is in vb  for i as integer  list items count-1 to 0 step -1      list items removeat i  next

User · Answer

Jefferson is right  you have to do it backwards   Here s the c  equivalent   for  var i    list Items Count - 1  i  gt   0  i--        list Items RemoveAt i

User · Answer

while listbox Items Remove s     should work  as well  However  I think the backwards solution is the fastest

User · Answer

Everyone else has posted  going backwards  answer  so I ll give the alternative  create a list of items you want to remove  then remove them at the end   List lt string gt  removals   new List lt string gt     foreach  string s in listBox1 Items        MessageBox Show s         do stuff with  s       removals Add s      foreach  string s in removals        listBox1 Items Remove s       Sometimes the  work backwards  method is better  sometimes the above is better - particularly if you re dealing with a type which has a RemoveAll collection  method  Worth knowing both though

User · Answer

Jefferson is right  you have to do it backwards   Here s the c  equivalent   for  var i    list Items Count - 1  i  gt   0  i--        list Items RemoveAt i

User · Answer

while listbox Items Remove s     should work  as well  However  I think the backwards solution is the fastest

User · Answer

You have to go through the collection from the last item to the first  this code is in vb  for i as integer  list items count-1 to 0 step -1      list items removeat i  next

[c#] How do I loop through items in a list box and then remove those item?

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