Order the lines in a file by the last character on the line

Can you please help me with this: I want to build a method in C# which will order a lot of files by the following rule开发者_运维百科 every line contains strings and the last character in every line is an int. I want to order the lines in the file by this last character, the int.

Thanks

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To order ascending by the last character, interpreted as an integer you could do:

var orderedLines= File.ReadAllLines(@"test.txt")
                        .OrderBy(line => Convert.ToInt32(line[line.Length-1]))
                        .ToList();

Edit:

With the clarification in your comment - integer following a space character, can be more than one digit:

var orderedLines= File.ReadAllLines(@"test.txt")
                      .OrderBy(line => Convert.ToInt32(line.Substring(line.LastIndexOf(" ")+1, 
                                                                        line.Length - line.LastIndexOf(" ")-1)))
                      .ToList();

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You could do something like this, where filename is the name of your file:

// Replace with the actual name of your file
string fileName = "MyFile.txt";

// Read the contents of the file into memory 
string[] lines = File.ReadAllLines(fileName);

// Sort the contents of the file based on the number after the last space in each line
var orderedLines = lines.OrderBy(x => Int32.Parse(x.Substring(x.LastIndexOf(' '))));

// Write the lines back to the file
File.WriteAllText(fileName, string.Join(Environment.NewLine, orderedLines));

This is just a rough outline; hopefully it's helpful.

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File.WriteAllLines(
    pathToWriteTo,
    File.ReadLines(pathToReadFrom)
        .OrderBy(s => Convert.ToInt32(s.Split(' ').Last()))
);

If the file is large, this could be ineffective as this method of sorting effectively requires reading the entire file into memory.

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Assuming you want more than single digit integers and that you have a separation character between the filename and the rest (we'll call it 'splitChar') which can be any character at all:

from string str in File.ReadAllLines(fileName) 
    let split = str.Split(splitChar)
    orderby Int32.Parse(split[split.Count()-1]) 
    select str

will get you a sequence of strings in order of the integer value of the last grouping (separated by the split character).

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Maybe one of these links can help you by sorting it the natural way:

• Natural Sorting in C#
• Sorting for Humans : Natural Sort Order