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Category Archives: regular expressions
Use string extension methods to validate Social Security numbers in C#
This example defines three extension methods that return true if strings contain Social Security numbers. Recall that you must add extension methods to a static class and that the methods must be static. This example begins by defining a Matches … Continue reading
Move a window with a title that matches a pattern in C#
The example Set another application’s size and position in C# uses the FindWindow API function to find a window with a given title. Unfortunately FindWindow only finds the window if the title is an exact match. If you only know … Continue reading
Remove non-digits or non-letters from a string in C#
Sometimes you might want to extract only the digits, letters, or some other group of characters from a string. You could loop through the string examining each character individually. Fortunately there’s a much easier way to do this. The regular … Continue reading
List unique words in a text file in C#
This example uses regular expressions and LINQ to list the unique words contained in a text file in C#. When you enter the name of a file and click List Words, the following code executes. // List the words in … Continue reading
Posted in files, LINQ, regular expressions
Tagged C#, C# programming, count words, example, example program, files, find words, LINQ, regular expressions, unique words, Windows Forms programming
1 Comment
Understand C# regular expression symbols
The following table shows useful regular expression symbols, commands, and other items that you can use in regular expressions in C# programs. Item Purpose \ Either begins a special symbol such as \n or escapes the following character ^ Matches … Continue reading
Replace text in the lines of a string in C#
This example uses the following code to replace text in the lines of a string. private void btnGo_Click(object sender, EventArgs e) { try { Regex reg_exp = new Regex(txtPattern.Text); lblResult.Text = reg_exp.Replace( txtInput.Text, txtReplacementPattern.Text); } catch (Exception ex) { MessageBox.Show(ex.Message); … Continue reading
Posted in regular expressions, strings
Tagged C#, C# programming, example, example program, parse, parsing, patterns, regular expressions, replace, replace lines, string parsing, strings, Windows Forms programming
6 Comments
Replace text matching a pattern in C#
This example uses the following code to replace text matching a pattern within a string. // Make the replacements. private void btnGo_Click(object sender, EventArgs e) { Regex reg_exp = new Regex(txtPattern.Text); lblResult.Text = reg_exp.Replace( txtTestString.Text, txtReplacementPattern.Text); } This code creates … Continue reading
Show regular expression matches in C#
When you click the Go button, the program uses the following code to display regular expression matches in a string. Regex reg_exp = new Regex(txtPattern.Text); MatchCollection matches = reg_exp.Matches(txtTestString.Text); rchResults.Text = txtTestString.Text; foreach (Match a_match in matches) { rchResults.Select(a_match.Index, a_match.Length); … Continue reading
Use regular expressions to rename files within a date range and that match a pattern in C#
This example extends the example Use regular expressions to rename files that match a pattern in C# to let you rename files within a date range. See the previous example for most of the details. This post describes the changes … Continue reading
Use regular expressions to rename files that match a pattern in C#
This example shows how to use regular expressions to rename files. To use the program, enter a directory name and a file pattern. Also enter regular expression find and replace patterns. When you click Preview Changes, the program searches the … Continue reading
Posted in files, regular expressions
Tagged C#, C# programming, example, example program, files, pattern matching, patterns, Regex, regular expressions, rename files, Windows Forms programming
4 Comments