c# - Regex to remove trailing whitespace and multiple blank lines

C# - Regex to remove trailing whitespace and multiple blank lines

To remove trailing whitespace from each line and multiple blank lines from a string in C#, you can use regular expressions. Here's how you can achieve this:

  1. Remove trailing whitespace from each line: Use a regex pattern to find trailing whitespace and replace it with an empty string.

  2. Remove multiple blank lines: Use another regex pattern to collapse multiple blank lines into a single blank line.

Step-by-Step Solution

1. Removing Trailing Whitespace

The regex pattern \s+$ matches any trailing whitespace (spaces, tabs) at the end of each line.

2. Removing Multiple Blank Lines

The regex pattern (\r?\n){2,} matches two or more consecutive new lines (Windows style \r\n or Unix style \n). Replace these with a single newline.

Example Implementation

Here's a complete example in C#:

using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = @" This is a line with trailing spaces. This is another line with trailing tabs. This is a line with no trailing spaces. This line should be right after the previous one with a single blank line in between. "; // Step 1: Remove trailing whitespace from each line string withoutTrailingWhitespace = Regex.Replace(input, @"\s+$", "", RegexOptions.Multiline); // Step 2: Remove multiple blank lines string result = Regex.Replace(withoutTrailingWhitespace, @"(\r?\n){2,}", Environment.NewLine + Environment.NewLine); Console.WriteLine("Original Input:"); Console.WriteLine(input); Console.WriteLine("Processed Output:"); Console.WriteLine(result); } }

Explanation

  1. Removing Trailing Whitespace:

    string withoutTrailingWhitespace = Regex.Replace(input, @"\s+$", "", RegexOptions.Multiline);
    • @"\s+$": This pattern matches one or more whitespace characters at the end of a line.
    • RegexOptions.Multiline: This option treats the input as having multiple lines, so ^ and $ match the start and end of each line respectively.

  2. Removing Multiple Blank Lines:

    string result = Regex.Replace(withoutTrailingWhitespace, @"(\r?\n){2,}", Environment.NewLine + Environment.NewLine);
    • @"(\r?\n){2,}": This pattern matches two or more consecutive newline sequences.
    • Environment.NewLine + Environment.NewLine: This replacement ensures that multiple blank lines are replaced with a single blank line.

Output

The result string will have trailing whitespace removed from each line and multiple blank lines reduced to a single blank line.

Original Input: This is a line with trailing spaces. This is another line with trailing tabs. This is a line with no trailing spaces. This line should be right after the previous one with a single blank line in between. Processed Output: This is a line with trailing spaces. This is another line with trailing tabs. This is a line with no trailing spaces. This line should be right after the previous one with a single blank line in between.

This approach ensures that your text is cleaned up by removing unwanted trailing whitespace and collapsing multiple blank lines into single blank lines.

Examples

  1. C# regex remove trailing whitespace example

    • Description: This query seeks an example of using a regex pattern in C# to remove trailing whitespace (spaces, tabs) from strings.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Hello world! \t\n"; string cleaned = Regex.Replace(input, @"\s+$", ""); Console.WriteLine($"Cleaned string: '{cleaned}'"); } }

  2. C# regex remove multiple blank lines

    • Description: This query looks for a C# code snippet using regex to remove multiple consecutive blank lines from a string.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = "Line 1\n\n\nLine 2\n\nLine 3\n\n\n\n\nLine 4"; string cleaned = Regex.Replace(input, @"(\r?\n){2,}", "\n"); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  3. C# regex trim trailing whitespace and blank lines

    • Description: This query focuses on combining regex patterns in C# to trim trailing whitespace and remove multiple consecutive blank lines from text.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Text with trailing spaces \n\n\n\n\n\n\n\n"; string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(\r?\n){2,}", ""); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  4. C# regex remove trailing whitespace from lines

    • Description: This query seeks a C# example using regex to remove trailing whitespace from each line of a multi-line string.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with spaces \nLine 2 with spaces \nLine 3 with spaces \n"; string cleaned = Regex.Replace(input, @"\s+$", "", RegexOptions.Multiline); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  5. C# regex trim multiple blank lines and spaces

    • Description: This query looks for a C# code snippet to trim multiple consecutive blank lines and any leading/trailing spaces using regex.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with spaces \n\n\nLine 2 with spaces \n\n\n\n\nLine 3 with spaces \n\n\n"; string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(\r?\n){2,}", "", RegexOptions.Multiline); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  6. C# regex remove trailing whitespace and empty lines

    • Description: This query seeks an example of using regex in C# to remove both trailing whitespace and completely empty lines from text.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with spaces \n\nLine 2 with spaces \n\n\nLine 3 with spaces \n\n"; string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(^[\r\n]*|[\r\n]+\z)", "", RegexOptions.Multiline); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  7. C# regex remove trailing spaces and blank lines from file

    • Description: This query looks for C# code to read a file, apply a regex pattern to remove trailing spaces and blank lines, and output the cleaned content.
    • Code Implementation:
      using System; using System.IO; using System.Text.RegularExpressions; class Program { static void Main() { string filePath = "path/to/your/file.txt"; string input = File.ReadAllText(filePath); string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(\r?\n){2,}", "", RegexOptions.Multiline); // Example: Write cleaned content back to the file File.WriteAllText(filePath, cleaned); Console.WriteLine("File cleaned successfully."); } }

  8. C# regex trim whitespace and empty lines from string

    • Description: This query seeks a C# snippet to trim all leading/trailing whitespace and remove completely empty lines from a string using regex.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with spaces \n\nLine 2 with spaces \n\n\n\nLine 3 with spaces \n\n"; string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(^[\r\n]*|[\r\n]+\z)", ""); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  9. C# regex remove extra spaces and blank lines

    • Description: This query focuses on using C# regex to remove extra spaces (leading/trailing) and multiple blank lines from a text block.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with spaces \n\nLine 2 with spaces \n\n\n\nLine 3 with spaces \n\n"; string cleaned = Regex.Replace(input, @"(\s*$)|(^\s*)|(\r?\n){2,}", ""); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

  10. C# regex trim trailing whitespace in lines

    • Description: This query seeks an example of using regex in C# to trim trailing whitespace from each line of a multi-line string.
    • Code Implementation:
      using System; using System.Text.RegularExpressions; class Program { static void Main() { string input = " Line 1 with trailing spaces \nLine 2 with trailing spaces \nLine 3 with trailing spaces \n"; string cleaned = Regex.Replace(input, @"\s+$", "", RegexOptions.Multiline); Console.WriteLine($"Cleaned string:\n{cleaned}"); } }

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