String.IndexOf Method (String, Int32, Int32)
Reports the zero-based index of the first occurrence of the specified string in this instance. The search starts at a specified character position and examines a specified number of character positions.
Assembly: mscorlib (in mscorlib.dll)
- Type: System.String
The string to seek.
- Type: System.Int32
The search starting position.
- Type: System.Int32
The number of character positions to examine.
Index numbering starts from 0 (zero). The startIndex parameter can range from 0 to the length of the string instance.
This method performs a word (case-sensitive and culture-sensitive) search using the current culture. The search begins at startIndex and continues to startIndex + count -1. The character at startIndex + count is not included in the search.
Character sets include ignorable characters, which are characters that are not considered when performing a linguistic or culture-sensitive comparison. In a culture-sensitive search, if value contains an ignorable character, the result is equivalent to searching with that character removed. If value consists only of one or more ignorable characters, the method always returns startIndex, which is the character position at which the search begins. In the following example, the method is used to find the position of a soft hyphen (U+00AD) followed by an "m" starting in the third through sixth character positions in two strings. Only one of the strings contains the required substring. If the example is run on the .NET Framework 4 or later, in both cases, because the soft hyphen is an ignorable character, the method returns the index of "m" in the string when it performs a culture-sensitive comparison. Note that in the case of the first string, which includes the soft hyphen followed by an "m", the method fails to return the index of the soft hyphen but instead returns the index of the "m".Notes to Callers
As explained in Best Practices for Using Strings in the .NET Framework, we recommend that you avoid calling string comparison methods that substitute default values and instead call methods that require parameters to be explicitly specified. To use the comparison rules of the current culture to perform this operation, call the IndexOf(String, Int32, Int32, StringComparison) method overload with a value of StringComparison.CurrentCulture for its comparisonType parameter.
The following example finds the index of all occurrences of the string "he" within a substring of another string. Note that the number of characters to be searched must be recalculated for each search iteration.
.NET FrameworkSupported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
Portable Class LibrarySupported in: Portable Class Library
.NET for Windows Store appsSupported in: Windows 8
.NET for Windows Phone appsSupported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)