GroupCollection.Item Property (String)
Enables access to a member of the collection by string index.
Assembly: System (in System.dll)
Parameters
- groupname
- Type: System.String
The name of a capturing group.
Property Value
Type: System.Text.RegularExpressions.GroupThe member of the collection specified by groupname.
groupName can be either the name of a capturing group that is defined by the (?<name>) element in a regular expression, or the string representation of the number of a capturing group that is defined by a grouping construct. For more information about groups in regular expressions, see Grouping Constructs in Regular Expressions.
If groupname is not the name of a capturing group in the collection, or if groupname is the name of a capturing group that has not been matched in the input string, the method returns a Group object whose Group.Success property is false and whose Group.Value property is String.Empty.
The following example defines a regular expression that consists of two named groups. The first group, numbers, captures one or more consecutive digits. The second group, letter, matches a single character. Because the regular expression engine looks for zero or one occurrence of the pattern defined by the numbers group, the numbers group is not always present even if a match is successful. The example then illustrates the result when the Item(String) property is used to retrieve an unmatched group, a matched group, and a group that is not defined in the regular expression. The example defines a regular expression pattern (?<numbers>\d+)*(?<letter>\w)\k<letter>, which is interpreted as shown in the following table.
Pattern | Description |
|---|---|
(?<numbers>\d+)* | Match one or more occurrence of a decimal digit. Name this the numbers capturing group. Match this pattern either zero or one time. |
(?<letter>\w) | Match a single word character. Name this the letter capturing group. |
\k<letter> | Match the string captured by the letter capturing group. |
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)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
