How to pass a single object to a params object

Question

I have a method which takes params object   such as   void Foo params object   items        Console WriteLine items 0        When I pass two object arrays to this method  it works fine   Foo new object     object  1    object  2     new object     object  3    object  4          Output  System Object     But when I pass a single object    it does not take my object   as the first param  instead it takes its all elements like I wanted to pass them one by one   Foo new object     object  1    object  2         Output  1  expected  System Object     How do I pass a single object   as a first argument to a params array

User · Answer

new      object  0   object  null   object  false

User · Answer

One option is you can wrap it into another array   Foo new object    new object     object  1    object  2          Kind of ugly  but since each item is an array  you can t just cast it to make the problem go away    such as if it were Foo params object items   then you could just do   Foo  object  new object     object  1    object  2        Alternatively  you could try defining another overloaded instance of Foo which takes just a single array   void Foo object   item           Somehow don t duplicate Foo object    and        Foo params object    without making an infinite        recursive call    maybe something like        FooImpl params object   items  and then this        could invoke it via         FooImpl new object     item

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The params parameter modifier gives callers a shortcut syntax for passing multiple arguments to a method  There are two ways to call a method with a params parameter   1  Calling with an array of the parameter type  in which case the params keyword has no effect and the array is passed directly to the method   object   array   new      1    2         Foo receives the  array  argument directly  Foo  array      2  Or  calling with an extended list of arguments  in which case the compiler will automatically wrap the list of arguments in a temporary array and pass that to the method      Foo receives a temporary array containing the list of arguments  Foo   1    2         This is equivalent to  object   temp   new      1    2     Foo  temp        In order to pass in an object array to a method with a  params object    parameter  you can either   1  Create a wrapper array manually and pass that directly to the method  as mentioned by lassevk   Foo  new object     array          Equivalent to calling convention 1    2  Or  cast the argument to object  as mentioned by Adam  in which case the compiler will create the wrapper array for you   Foo   object array        Equivalent to calling convention 2      However  if the goal of the method is to process multiple object arrays  it may be easier to declare it with an explicit  params object      parameter  This would allow you to pass multiple arrays as arguments   void Foo  params object     arrays       foreach  object   array in arrays            process array            Foo  new      1    2     new      3    4           Equivalent to  object     arrays   new       new      1    2       new      3    4       Foo  arrays        Edit  Raymond Chen describes this behavior and how it relates to the C  specification in a new post

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This is a one line solution involving LINQ   var elements   new String      1    2    3     Foo elements Cast lt object gt    ToArray

User · Answer

You need to encapsulate it into another object   array  like this   Foo new Object     new object     object  1    object  2

User · Answer

A simple typecast will ensure the compiler knows what you mean in this case   Foo  object new object     object  1    object  2         As an array is a subtype of object  this all works out  Bit of an odd solution though  I ll agree

User · Answer

Another way to solve this problem  it s not so good practice but looks beauty    static class Helper       public static object AsSingleParam this object   arg               return  object arg            Usage   f new object     1  2  3   AsSingleParam

[c#] How to pass a single object[] to a params object[]

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