c# - how to have conditional params arguments to a function -

i have

public void foo(string name, params object[] args) 

i want call list of args can vary. need like

foo("yo",a,b,x==42?c); 

ie if x 42 pass in a,b,c otherwise pass in a,b. of course syntax doesn't work. know marshal args list , pass list function, messy way code organized. there syntax magic can use

edit: let me add concrete case

var xml = new xdocument(....,    new xelement(....),    new xelement(....),    new xelement(....),    x==42? new xelement(.....),    new xelement(....),    new xelement(....)    .... 

you can use if statement:

if (x == 42)    foo("yo", a, b, c); else    foo("yo", a, b); 

you can't use ?: operator in case (at least, outside of function call), because foo has no return value. ?: operator must evaluate something, , must assigned else.

another option rid of duplicate function call use array or list params:

var parameters = new list<object> { a, b };  if (x == 42)    parameters.add(c);  foo("yo", parameters); 

and if wanted ?: in there, work, too:

foo("yo", x == 42 ? new object[] { a, b, c } : new object[] { a, b }); 

for more specific question xdocument/xelement constructor calls, might want use add calls rather 1 long series of constructor calls. can make them conditional. is, think should able you're asking doing this:

xelement elementprecedingoptionalelement = new xelement(...);  var xml = new xdocument(....,    new xelement(...),    new xelement(...),    elementprecedingoptionalelement,    new xelement(...),    new xelement(...) );  if (x == 42)    elementprecedingoptionalelement.addafterself(new xelement(...)); 

using add calls this:

xdocument xml = new xdocument(); xelement root = new xelement("root"); xml.add(root);  root.add(new xelement("item1")); root.add(new xelement("item2")); if (x == 42)    root.add(new xelement("item2.5")); root.add(new xelement("item3")); root.add(new xelement("item4")); 

actually, 1 last version closer asking this, seems work:

var xml = new xdocument(....,    new xelement(...),    new xelement(...),    new xelement(...),    x == 42       ? new xelement(...)       : null,    new xelement(...),    new xelement(...) );