Detect how each line of a file ends in C#

user_2848242 0
Viewed 578

Is it possible to loop for each line in a file and check how it ends (LF / CRLF):

using(StreamReader sr = new StreamReader("TestFile.txt")) 
{
    string line;
    while ((line = sr.ReadLine()) != null) 
    {
        if (line.contain("\r\n") 
        {
            Console.WriteLine("CRLF");
        }
        else if (line.contain("\n") 
        {
            Console.WriteLine("LF");
        }
    }
}
streamreader c#
2 Answers

You'll have to use Read to get each character and check for the line terminators. You'll also have to keep track if you've seen a carriage return so you'll know if you're dealing with a CRLF or just a LF when you see a line feed. And you'll have to check for a trailing CR after the loop is done.

using(StreamReader sr = new StreamReader("TestFile.txt")) 
{
    bool returnSeen = false;
    while (sr.Peek() >= 0) 
    {
        char c = sr.Read();
        if (c == '\n')
        {
            Console.WriteLine(returnSeen ? "CRLF" : "LF");
        }
        else if(returnSeen)
        {
            Console.WriteLine("CR");
        }

        returnSeen = c == '\r';
    }

    if(returnSeen) Console.WriteLine("CR");
}

Note you can construct the lines from the characters you read and you can change this to use the overload of Read that read into a buffer and search the result for the line terminators for better performance.

user_3029180

you can this code:

private const char CR = '\r';  
private const char LF = '\n';  
private const char NULL = (char)0;

public static long CountLines(Stream stream)  
{
    //Ensure.NotNull(stream, nameof(stream));

    var lineCount = 0L;

    var byteBuffer = new byte[1024 * 1024];
    var prevChar = NULL;
    var pendingTermination = false;

    int bytesRead;
    while ((bytesRead = stream.Read(byteBuffer, 0, byteBuffer.Length)) > 0)
    {
        for (var i = 0; i < bytesRead; i++)
        {
            var currentChar = (char)byteBuffer[i];

            if (currentChar == NULL) { continue; }
            if (currentChar == CR || currentChar == LF)
            {
                if (prevChar == CR && currentChar == LF) { continue; }

                lineCount++;
                pendingTermination = false;
            }
            else
            {
                if (!pendingTermination)
                {
                    pendingTermination = true;
                }
            }
            prevChar = currentChar;
        }
    }

    if (pendingTermination) { lineCount++; }
    return lineCount;
}
user_150195360
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