Searches for the specified substring and returns the zero-based index of the last occurrence within the section of the source string that extends from the beginning of the string to the specified index.
Syntax
Parameters
- source
- value
- startIndex
Returns
The zero-based index of the last occurrence of value, if found, within the section of source that extends from the beginning of source to startIndex; otherwise, -1. Returns startIndex if value is an ignorable character.
Remarks
The source string is searched backward starting at startIndex and ending at the beginning of the string.
This overload performs a culture-sensitive search. A Unicode value representing a precomposed character, such as the ligature "Æ" (U+00C6), might be considered equivalent to any occurrence of the character's components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture. To perform an ordinal (culture-insensitive) search, where the Unicode values are compared, you should call one of the overloads that has a parameter of type System.Globalization.CompareOptions and use the CompareOptions.Ordinal value.
When possible, you should call string comparison methods that have a parameter of type System.Globalization.CompareOptions to specify the kind of comparison expected. As a general rule, use linguistic options (using the current culture) for comparing strings displayed in the user interface and specify CompareOptions.Ordinal or CompareOptions.OrdinalIgnoreCase for security comparisons.
Requirements
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0