C # Dictionary known value gets the corresponding key

1: Cycle through the calendar, divided into ergodic key-value key value pairs and traverse all key two forms

2: Using LINQ Query method

1     Private voidGetdictkeybyvalue ()2     {3dictionary<int,string> dict =Newdictionary<int,string>();4Dict. ADD (1,"1");5Dict. ADD (2,"2");6Dict. ADD (3,"2");7Dict. ADD (4,"4");8 9         //foreach KeyValuePairTenlist<int> list =Newlist<int>(); One         foreach(keyvaluepair<int,string> kvpinchdict) A         { -             if(KVP. Value.equals ("2")) -             { theList. ADD (KVP. Key);//kvp. Key; -             } -         } -  +         //foreach dic. Keys - list. Clear (); +         foreach(intKeyinchDict. Keys) A         { at             if(Dict[key]. Equals ("2")) -             { -List. ADD (key);//Key -             } -         } -  in         //Linq -list<int> keylist = Dict. Where (q = Q.value = ="2") to. Select (q = q.key). tolist<int> ();//Get all keys +  -Keylist = ( fromQinchDict the                     whereQ.value = ="2" *                     SelectQ.key). tolist<int> ();//Get all keys $ Panax Notoginseng         varFirstkey = Dict. FirstOrDefault (q = Q.value = ="2"). Key;//get first key -}

C # Dictionary known value gets the corresponding key