c# error while copying arraylist to array

Question

I have 2 arraylists in my project, list1, and list2. (both contains 9 String values, car1, car2, car3 and so on.

I also have an string array, called store_numbers which can contain 52 String elements. Now I wanna copy my values from list1 and list2 to the array. By doing :

  list1.CopyTo(store_numbers,0);

Which I think is the right way I get the error message

At least one element in the source could not be cast down to the destination array type

Anyone who knows how I can Fix this?

Thanks!

The error is shouting type mismatch between your arrays; can you post your code (at least the definitions of all arrays concerned)? — dolphy
– dolphy, Commented Jun 14, 2011 at 14:55
Make sure they are all strings or better yet, post the exact code. — Xaisoft
– Xaisoft, Commented Jun 14, 2011 at 15:06

Joe White · Accepted Answer · 2011-06-14 14:55:01Z

12

You have something in your ArrayList that isn't a string.

The best fix is not to use ArrayList! It's been obsolete since .NET 2.0 came out. Use a List<string> instead. Then the compiler will prevent you from putting a non-string in the list in the first place, and your copy should work fine.

answered Jun 14, 2011 at 14:55

Joe White

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laz Over a year ago

Thanks for your answer! My arraylists contains values like "car1","car2" and so on!

Xaisoft · Accepted Answer · 2011-06-14 15:11:06Z

1

You probably have something close to this:

ArrayList list1 = new ArrayList{"car1",2,"car3","car4","car5",
                                "car6","car7","car8","car9"};

string[] store_numbers = new string[] {"10","11","12","13","14","15",
                                       "16","17","18"};

list1.CopyTo(store_numbers,0);

The above will throw the following error:

 `At least one element in the source array could not be cast 
  down to the destination array type.`

There is the number 2 in list1, that is why you get the error in this case. Change to List<string> to avoid this.

edited Jun 14, 2011 at 15:11

answered Jun 14, 2011 at 15:04

Xaisoft

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Comments

Anders Abel · Accepted Answer · 2011-06-14 14:57:05Z

1

Are you really sure that the arraylists only contain strings? The error message indicates that at least one object in one of the arraylists isn't a string. If you set a breakpoint at the place where the problem occurs you should be able to look at the arraylist contents.

Also you shouldn't be using ArrayList at all - it is deprecated. Use List<String> to get type safety.

answered Jun 14, 2011 at 14:57

Anders Abel

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laz Over a year ago

Thanks for answer! My arraylists contains values like "car1","car2" and so on!

Amir Ismail · Accepted Answer · 2011-06-14 14:58:07Z

0

make sure all items in your ArrayList have the same datatype.if not, you have to convert all items to string before copying it.

answered Jun 14, 2011 at 14:58

Amir Ismail

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