How to get all checked out files in SharePoint client object model c#?

Question

I need to get all checked out files from a document library. I am trying by following query.

CamlQuery camlQuery = new CamlQuery();
camlQuery.ViewXml = @
"<View>
       <Query>
              <Where>
                <IsNotNull>
                    <FieldRef Name='CheckoutUser' />
                </IsNotNull>
              </Where>
         </Query>
 </View>";

Above query returns the documents those are checked out by current user. I need to get all checked out documents (checked out by any use).

update

I have required columns. When users drag and drop files without filling out those columns it's remain invisible to others. Whenever users upload document, it goes to the Manage files which have no checked in version. I need to get those files grammatically.

Answer 1

Replace

<Where>
   <IsNotNull>
       <FieldRef Name='CheckoutUser' />                                            
   </IsNotNull>
</Where>

with

<Where>
    <Geq>
      <FieldRef Name="CheckoutUser" LookupId="TRUE" />
              <Value Type="int">0</Value>
    </Geq>
</Where>