Interface ISearch

An object able to search for items in direct random access structures, such as lists and arrays, which are monodimensional and implement the interface.

Namespace: MoreStructures.Lists.Searching
Assembly: MoreStructures.dll
Syntax
public interface ISearch
Remarks

In .NET, random access structures usually have an indexer defined, which takes as an index the address of the item in the data structure (usually an integer). Most random access structures (but not all) inherit and define .
A notable exception is System.String, which has an indexer (System.String.Chars(System.Int32)), but does not implement . For System.String, specific optimizations are done, to ensure random access in O(1) time.

Methods

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First<T>(IEnumerable<T>, T, Nullable<IComparer<T>>, Nullable<Int32>, Nullable<Int32>)

Find the index of the first item in the sub-sequence of items of source from fromIndex to toIndex included, which is equal to item.

Declaration
int First<T>(IEnumerable<T> source, T item, IComparer<T>? comparer = null, int? fromIndex = null, int? toIndex = null)
Parameters
Type Name Description
IEnumerable<T> source

The enumerable where to search for item.
T item

The item to search for.
System.Nullable<IComparer<T>> comparer

The comparer to be used when performing the search. If not specified, is used.
System.Nullable<System.Int32> fromIndex

The first index, marking the begin of the sub-sequence of source where to search. If not specified, 0 is used.
System.Nullable<System.Int32> toIndex

The last index, marking the end of the sub-sequence of source where to search. If not specified, is called on source to calculate the count of items, and count - 1 is used. If source is a System.String, however, System.String.Length is used instead.
Returns
Type Description
System.Int32

The first index of item in source.
Type Parameters
Name Description
T

The type of items of source. Must be comparable. If it is System.String, random access is done in O(1) via System.String.Chars(System.Int32). Otherwise, random access is done via the generic LINQ method , which is O(n) or O(1) dependending on the concretion.
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FirstAll<T>(IEnumerable<T>, Nullable<IComparer<T>>, Nullable<Int32>, Nullable<Int32>)

Find the indexes of the first occurrence of each item in the sub-sequence of items of source from fromIndex to toIndex included.

Declaration
IDictionary<T, int> FirstAll<T>(IEnumerable<T> source, IComparer<T>? comparer = null, int? fromIndex = null, int? toIndex = null)
Parameters
Type Name Description
IEnumerable<T> source

The enumerable.
System.Nullable<IComparer<T>> comparer

The comparer to be used when performing the search, to tell apart different items. If not specified, is used.
System.Nullable<System.Int32> fromIndex

The first index, marking the begin of the sub-sequence of source where to search. If not specified, 0 is used.
System.Nullable<System.Int32> toIndex

The last index, marking the end of the sub-sequence of source where to search. If not specified, is called on source to calculate the count of items, and count - 1 is used. If source is a System.String, however, System.String.Length is used instead.
Returns
Type Description
IDictionary<T, System.Int32>

A containing the 0-based index first occurrence of each item, indexed by the item itself.
Type Parameters
Name Description
T

The type of items of source. Must be comparable and non-null, since it is used as key to index first occurrence indexes in the output .
If it is System.String, random access is done in O(1) via System.String.Chars(System.Int32). Otherwise, random access is done via the generic LINQ method , which is O(n) or O(1) dependending on the concretion.
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Interval<T>(IEnumerable<T>, T, Nullable<IComparer<T>>, Nullable<Int32>, Nullable<Int32>)

Find the indexes of the first and last items in the sub-sequence of items of source from fromIndex to toIndex included, which is equal to item.

Declaration
(int first, int last) Interval<T>(IEnumerable<T> source, T item, IComparer<T>? comparer = null, int? fromIndex = null, int? toIndex = null)
Parameters
Type Name Description
IEnumerable<T> source

The enumerable where to search for item.
T item

The item to search for.
System.Nullable<IComparer<T>> comparer

The comparer to be used when performing the search. If not specified, is used.
System.Nullable<System.Int32> fromIndex

The first index, marking the begin of the sub-sequence of source where to search. If not specified, 0 is used.
System.Nullable<System.Int32> toIndex

The last index, marking the end of the sub-sequence of source where to search. If not specified, is called on source to calculate the count of items, and count - 1 is used. If source is a System.String, however, System.String.Length is used instead.
Returns
Type Description
System.ValueTuple<System.Int32, System.Int32>

The first and last index, marking the end of the sub-sequence of source where to search.
Type Parameters
Name Description
T

The type of items of source. Must be comparable. If it is System.String, random access is done in O(1) via System.String.Chars(System.Int32). Otherwise, random access is done via the generic LINQ method , which is O(n) or O(1) dependending on the concretion.
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Last<T>(IEnumerable<T>, T, Nullable<IComparer<T>>, Nullable<Int32>, Nullable<Int32>)

Find the index of the last item in the sub-sequence of items of source from fromIndex to toIndex included, which is equal to item.

Declaration
int Last<T>(IEnumerable<T> source, T item, IComparer<T>? comparer = null, int? fromIndex = null, int? toIndex = null)
Parameters
Type Name Description
IEnumerable<T> source

The enumerable where to search for item.
T item

The item to search for.
System.Nullable<IComparer<T>> comparer

The comparer to be used when performing the search. If not specified, is used.
System.Nullable<System.Int32> fromIndex

The first index, marking the begin of the sub-sequence of source where to search. If not specified, 0 is used.
System.Nullable<System.Int32> toIndex

The last index, marking the end of the sub-sequence of source where to search. If not specified, is called on source to calculate the count of items, and count - 1 is used. If source is a System.String, however, System.String.Length is used instead.
Returns
Type Description
System.Int32

The first and last index, marking the end of the sub-sequence of source where to search.
Type Parameters
Name Description
T

The type of items of source. Must be comparable. If it is System.String, random access is done in O(1) via System.String.Chars(System.Int32). Otherwise, random access is done via the generic LINQ method , which is O(n) or O(1) dependending on the concretion.
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Nth<T>(IEnumerable<T>, T, Int32, Nullable<IComparer<T>>, Nullable<Int32>, Nullable<Int32>)

Find the index of the n-th occurence (0-based) of the item in the sub-sequence of items of source from fromIndex to toIndex included, which is equal to item.

Declaration
int Nth<T>(IEnumerable<T> source, T item, int occurrenceRank, IComparer<T>? comparer = null, int? fromIndex = null, int? toIndex = null)
Parameters
Type Name Description
IEnumerable<T> source
T item
System.Int32 occurrenceRank
System.Nullable<IComparer<T>> comparer
System.Nullable<System.Int32> fromIndex
System.Nullable<System.Int32> toIndex
Returns
Type Description
System.Int32

The n-th index, marking the end of the sub-sequence of source where to search.
Type Parameters
Name Description
T

The type of items of source. Must be comparable. If it is System.String, random access is done in O(1) via System.String.Chars(System.Int32). Otherwise, random access is done via the generic LINQ method , which is O(n) or O(1) dependending on the concretion.

Extension Methods