The following methods are IEnumerable <T> extension method:
Average calculating an average value; Min smallest element; Max the maximum element; Total Sum element; Count the number of elements;
Concat connecting two sequences; // Unoin all equivalent to sql
Contains sequence contains a specified element;
Distinct sequence acquired distinct elements;
Except obtaining the difference between two sets of sequences;
Intersect obtain the intersection of two sequences;
First get the first element in the sequence;
Single element to obtain a unique sequence number if an element is not, then the error;
FirstOrDefault obtain a first sequence of elements, an element if no default value is returned;
Linq only for paradigm sequence, IEnumerable <T>, for non-generic type, or may be Cast OfType
IEnumerable method:
Cast <TResult>: Linq due to the type of operation for the paradigm, the old version of .Net the like for non-generic type IEnumerable sequence can be converted to a paradigm sequence by Cast Method. ArrayList l; IEnumerable <int> il = l.Cast <int> ();
OfType <TResult>: Cast attempts to sequence all the elements are converted to type TResult, non-generic type sequence if to be converted contain other types, an error is reported. OfType is singled out only the sequence of the specified type conversion element to paradigm sequence.