| FindIndexT(IListT, PredicateT) | Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the list. |
| FindIndexT(IListT, Int32, PredicateT) | Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the ListT that extends from the specified index to the last element. |