Using Character Classes in .NET Encoding Code128 in .NET Using Character Classes

How to generate, print barcode using .NET, Java sdk library control with example project source code free download:
Using Character Classes using barcode generating for visual .net control to generate, create code 128b image in visual .net applications. GS1 DataBar Family The output fro .net framework Code 128 Code Set B m this program is:. matches: the a t: 0 matches: the at: 32. When using reg visual .net USS Code 128 ular expressions, we often want to check for patterns that include groups of characters. We can write a regular expression that consists of such a group by enclosing the group in brackets ([]).

The characters inside the brackets are called a character class. If we wanted to write a regular expression that matched any lowercase alphabetic character, we would write the expression like this: [abcdefghijklmnopqrstuvwxyz]. But that s fairly hard to write, so we can write a shorter version by indicating a range of letters using a hyphen: [a-z].

Here s how we can use this regular expression to match a pattern:. using System; using System.Text.RegularExpressions; class chapter8 { static void Main() { string str1 = "THE quick BROWN fox JUMPED over THE lazy DOG"; MatchCollection matchSet; matchSet = Regex.

Matches(str1, "[a-z]"); foreach (Match aMatch in matchSet) Console.WriteLine("Matches at: " + aMatch.Index); } }.

The letters ma visual .net Code128 tched are those that make up the words quick , fox , over , and lazy . Character classes can be formed using more than one group.

If we want to match both lowercase letters and uppercase letters, we can write this regular expression: [A-Za-z] . You can also write a character class consisting of digits, like this: [0 9], if you want to include all ten digits. We can create the reverse, or negation, of a character class by placing a caret ( ) before the character class.

For example, if we have the character class [aeiou] representing the class of vowels, we can write [ aeiou] to represent the consonants, or nonvowels.. PATTERN MATCHING AND TEXT PROCESSING If we combine Code 128A for .NET these three character classes, we form what is called a word in regular expression parlance. The regular expression looks like this: [A-Za-z0 9].

There is also a shorter character class we can use to express this same class: \w. The negation of \w, or the regular expression to express a nonword character (such as a mark of punctuation) is expressed by \W. The character class for digits ([0 9]) can also be written as \d (note that because a backslash followed by another character can be an escape sequence in C#, codes such as \d are written \\d in C# code to indicate a regular expression and not an escape code) the rst backslash), and the character class for nondigits ([ 0 9]) can be written as \D.

Finally, because a white space plays such an important role in text processing, \s is used to represent white space characters whereas \S represents non-white-space characters. We will examine using the white space character classes later when we examine the grouping constructs..

MODIFYING REGULAR EXPRESSIONS USING ASSERTIONS C# includes a .net vs 2010 Code 128B set of operators you can add to a regular expression that change the behavior of the expression without causing the regular expression engine to advance through the string. These operators are called assertions.

The rst assertion we ll examine causes a regular expression to nd matches only at the beginning of a string or a line. This assertion is made using the caret symbol ( ). In the following program, the regular expression matches strings that have the letter h only as the rst character in the string.

An h in other places is ignored. Here s the code:. using System; using System.Text.RegularExpressions; class chapter8 { static void Main() { string[] words = new string[]{"heal", "heel", "noah", "techno"}; string regExp = "^h"; Match aMatch; foreach (string word in words) if (Regex.

IsMatch(word, regExp)) { aMatch = Regex.Match(word, regExp);. Using Grouping Constructs Console.WriteL ine("Matched: " + word + " at position: " + aMatch.Index); } } }.

The output of .net framework barcode 128 this code shows that just the strings heal and heel match. There is also an assertion that causes a regular expression to nd matches only at the end of the line.

This assertion is the dollar sign ($). If we modify the previous regular expression as:. string regExp = "h$";. noah is the Code 128 Code Set B for .NET only match found. Another assertion you can make in a regular expression is to specify that all matches can occur only at word boundaries.

This means that a match can only occur at the beginning or end of a word that is separated by spaces. This assertion is made with \b. Here s how the assertion works:.

string words = "hark, what doth thou say, Harold "; string regExp = "\\bh";. This regular e Code 128C for .NET xpression matches the words hark and Harold in the string. There are other assertions you can use in regular expressions, but these are three of the most commonly used.

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