C# Cookbook

8.9. Counting Lines of Text

Problem

You need to count lines of text within a string or within a file.

Solution

Read in the entire file and count the number of linefeeds, as shown in the following method:

using System;
using System.Text.RegularExpressions;
using System.IO;

public static long LineCount(string source, bool isFileName)
{
    if (source != null)
    {
        string text = source;

        if (isFileName)
        {
            FileStream FS = new FileStream(source, FileMode.Open, 
                                         FileAccess.Read, FileShare.Read);
            StreamReader SR = new StreamReader(FS);
            text = SR.ReadToEnd( );
            SR.Close( );
            FS.Close( );
        }

        Regex RE = new Regex("\n", RegexOptions.Multiline);
        MatchCollection theMatches = RE.Matches(text);

        // Needed for files with zero length
        //   Note that a string will always have a line terminator 
        //        and thus will always have a length of 1 or more
        if (isFileName)
        {
            return (theMatches.Count);
        }
        else
        {
            return (theMatches.Count) + 1;
        }
    }
    else
    {
        // Handle a null source here
        return (0);
    }
}

An alternative version of this method uses the StreamReader.ReadLine method to count lines in a file and a regular expression to count lines in a string:

public static long LineCount2(string source, bool isFileName) { if (source != null) { string text = source; long numOfLines = 0; if (isFileName) { FileStream FS = new FileStream(source, FileMode.Open, FileAccess.Read, FileShare.Read); StreamReader SR = new StreamReader(FS); while (text != null) { text = SR.ReadLine( ); if (text != null) { ++numOfLines; } } SR.Close( ); FS.Close( ); ...