void Main()
{
    var path = @"c:\sourceGit\speciesLatLon.txt";
    var inputLines = File.ReadAllLines(path);
    // Holds all the lines to be added to each output file
    var linesForCurrentSpeciesFile = new List<string>(); 
    // Read first row
    int i = 0;
    var currentSpecies = GetSpecies(inputLines[i]);
    // initialize hold value
    var holdValue = currentSpecies;
    // Initialize output values
    linesForCurrentSpeciesFile.Add(inputLines[i]);
    // Read next value
    i++;
    while( i < inputLines.Length )
    {
        currentSpecies = GetSpecies(inputLines[i]);
        if (currentSpecies !=  holdValue)
        {
            // output current file
            WriteSpeciesFile(holdValue, linesForCurrentSpeciesFile);
            // Initialize new output file by clearing out the previous
            linesForCurrentSpeciesFile.Clear();
            // update hold value with the value just examined.
            holdValue = currentSpecies;
        }
        // Add the current line to the output file
        linesForCurrentSpeciesFile.Add(inputLines[i]);
        i++;
    }
    // Write the output file because last row is equal to a break in the sequence
    WriteSpeciesFile(currentSpecies, linesForCurrentSpeciesFile);
}
// Define other methods and classes here
public string GetSpecies(string line)
{
    // return the first value of the input line
    return line.Split(new char[] {‘,‘})[0];
}
public void WriteSpeciesFile(string species, List<string> content)
{
    File.WriteAllLines(string.Format(@"C:\sourceGit\{0}.csv", species), content.ToArray());
}
原文:https://www.cnblogs.com/nichoxxc/p/9160534.html