The regular expression language in. A character in the input string must match one of a specified set of characters. For more information, see. A character in the input string must not match one of a specified set of characters. For more information, see. For more information, see. A character in the input string must be a member of a particular Unicode category or must fall within a contiguous range of Unicode characters for a match to succeed. For more information, see. A character in the input string must not be a member of a particular Unicode category or must not fall within a contiguous range of Unicode characters for a match to succeed. For more information, see. A character in the input string can belong to any of the Unicode categories that are appropriate for characters in words. For more information, see. A character in the input string can belong to any Unicode category that is not a word character. For more information, see. A character in the input string can be any Unicode separator character, as well as any one of a number of control characters. For more information, see. A character in the input string can be any character that is not a white-space character. For more information, see. A character in the input string can be any of a number of characters classified as Unicode decimal digits. For more information, see. A character in the input string can be anything other than a Unicode decimal digit. For more information, see. NET supports character class subtraction expressions, which enables you to define a set of characters as the result of excluding one character class from another character class. For more information, see. Note Character classes that match characters by category, such as to match word characters or to match a Unicode category, rely on the class to provide information about character categories. NET Framework 4 through the. This list of characters may be specified individually, as a range, or both. A character range is a contiguous series of characters defined by specifying the first character in the series, a hyphen - , and then the last character in the series. Two characters are contiguous if they have adjacent Unicode code points. Some common regular expression patterns that contain positive character classes are listed in the following table. Matches input, pattern ; foreach Match match in matches Console. Matches input, pattern For Each match As Match In matches Console. Match one or more non-white-space characters, but as few as possible. The following example matches words that begin with any capital letter. Matches input, pattern Console. Matches input, pattern Console. The list of characters may be specified individually, as a range, or both. A character range is a contiguous series of characters defined by specifying the first character in the series, a hyphen - , and then the last character in the series. Two characters are contiguous if they have adjacent Unicode code points. Two or more character ranges can be concatenated. Important A negative character group in a larger regular expression pattern is not a zero-width assertion. That is, after evaluating the negative character group, the regular expression engine advances one character in the input string. Some common regular expression patterns that contain negative character groups are listed in the following table. Matches input, pattern Console. Matches input, pattern Console. For more information, see. The following example illustrates the different behavior of the. Matches input, pattern Console. WriteLine ; foreach Match match in Regex. Matches input, pattern, RegexOptions. Matches input, pattern Console. WriteLine For Each match As Match In Regex. Matches input, pattern, RegexOptions. For more information, see and earlier in this topic. The following example provides an illustration by defining a regular expression that includes the period character. Matches input, pattern Console. Matches input, pattern Console. Value Next End Sub End Module ' The example displays the following output: ' this. Note Because it matches any character, the. For more information, see. For example, a particular character can be an uppercase letter represented by the Lu category , a decimal digit the Nd category , a math symbol the Sm category , or a paragraph separator the Zl category. Specific character sets in the Unicode standard also occupy a specific range or block of consecutive code points. For a list of category abbreviations, see the section later in this topic. For a list of named blocks, see the section later in this topic. } } Imports System. IsMatch input, pattern ' Displays True. Match zero or one white-space character. Match zero or one white-space character. For example, a particular character can be an uppercase letter represented by the Lu category , a decimal digit the Nd category , a math symbol the Sm category , or a paragraph separator the Zl category. Specific character sets in the Unicode standard also occupy a specific range or block of consecutive code points. For a list of category abbreviations, see the section later in this topic. For a list of named blocks, see the section later in this topic. Value Next End Sub End Module ' The example displays the following output: ' 164,091. A word character is a member of any of the Unicode categories listed in the following table. Category Description Ll Letter, Lowercase Lu Letter, Uppercase Lt Letter, Titlecase Lo Letter, Other Lm Letter, Modifier Mn Mark, Nonspacing Nd Number, Decimal Digit Pc Punctuation, Connector. For more information, see. This is the first capturing group. Match word, pattern ; if match. Index ; else Console. Match word, pattern If match. Category Description Ll Letter, Lowercase Lu Letter, Uppercase Lt Letter, Titlecase Lo Letter, Other Lm Letter, Modifier Mn Mark, Nonspacing Nd Number, Decimal Digit Pc Punctuation, Connector. For more information, see. The regular expression is interpreted as shown in the following table. This is the first capturing group. This is the second capturing group. Matches input, pattern { Console. Matches input, pattern Console. Count - 1 Console. It is equivalent to the escape sequences and Unicode categories listed in the following table. The regular expression is interpreted as shown in the following table. Matches input, pattern Console. Matches input, pattern Console. For more information, see. The second element in the match's object contains the matched string. The regular expression can be interpreted as shown in the following table. This is the first capturing group. Match zero or one white-space character. Matches input, pattern Console. Matches input, pattern Console. Groups 1 Next End Sub End Module ' The example displays the following output: ' This ' is ' the ' first ' sentence ' of ' the ' first ' paragraph. It tests whether an input string represents a valid telephone number in the United States and Canada. Match an optional opening parenthesis followed by three decimal digits, an optional closing parenthesis, and either a white-space character or a hyphen zero or one time. This is the first capturing group. IsMatch input, pattern Console. IsMatch input, pattern Then Console. It tests whether a string such as a part number consists of the appropriate combination of decimal and non-decimal characters. IsMatch input, pattern Console. IsMatch input, pattern Then Console. Category Description Lu Letter, Uppercase Ll Letter, Lowercase Lt Letter, Titlecase Lm Letter, Modifier Lo Letter, Other L All letter characters. This includes the Lu, Ll, Lt, Lm, and Lo characters. Mn Mark, Nonspacing Mc Mark, Spacing Combining Me Mark, Enclosing M All diacritic marks. This includes the Mn, Mc, and Me categories. Nd Number, Decimal Digit Nl Number, Letter No Number, Other N All numbers. This includes the Nd, Nl, and No categories. Pc Punctuation, Connector Pd Punctuation, Dash Ps Punctuation, Open Pe Punctuation, Close Pi Punctuation, Initial quote may behave like Ps or Pe depending on usage Pf Punctuation, Final quote may behave like Ps or Pe depending on usage Po Punctuation, Other P All punctuation characters. This includes the Pc, Pd, Ps, Pe, Pi, Pf, and Po categories. Sm Symbol, Math Sc Symbol, Currency Sk Symbol, Modifier So Symbol, Other S All symbols. This includes the Sm, Sc, Sk, and So categories. Zs Separator, Space Zl Separator, Line Zp Separator, Paragraph Z All separator characters. This includes the Zs, Zl, and Zp categories. Cc Other, Control Cf Other, Format Cs Other, Surrogate Co Other, Private Use Cn Other, Not Assigned no characters have this property C All control characters. This includes the Cc, Cf, Cs, Co, and Cn categories. You can determine the Unicode category of any particular character by passing that character to the method. The following example uses the method to determine the category of each element in an array that contains selected Latin characters. NET provides the named blocks listed in the following table. The set of supported named blocks is based on Unicode 4. Character class subtraction yields a set of characters that is the result of excluding the characters in one character class from another character class. The expression is evaluated from the innermost character range outward. You can use any character class with character class subtraction. Choose character classes for a character class subtraction expression that will yield useful results. Avoid an expression that yields an empty set of characters, which cannot match anything, or an expression that is equivalent to the original base group. The regular expression is interpreted as shown in the following table. In other words, match one or more occurrences of zero or an odd digit. Match input, pattern ; if match. Match input, pattern If match.
