| LastIndexOf(SpanChar, ReadOnlySpanChar, StringComparison) | Specifies the zero-based index of the last occurrence of a specified character sequence in span. A parameter specifies the type of search for the specified character sequence. |
| LastIndexOf(SpanChar, ReadOnlySpanChar, Int32, Int32, StringComparison) | Specifies the zero based index position of the last occurrence of a specified character sequence in span. The search begins at a specified character position and runs backwards to the beginning of the character span for a specified number of character positions. A parameter specifies the type of comparison to be performed when searching for the specified character sequence. |