Loop through set of files and check if it is comma

问题:

I need to loop through set of files and check if it is comma delimited or not in C#.I am very new to C#.Please help me with this.

Thanks in advance.

回答1:

As someone already pointed out it is not going to be easy solution. It could be very easy if every comma delimited file had a specified extension (for example: csv). If not the following algorigthm should work:

1. Retrieve all names (paths + names) of files in specified directory. If needed filter only those that may be of interest. Hint: take a look at System.IO.Directory and System.IO.File and System.IO.DirectoryInfo and System.IO.FileInfo
2. You have to examine every file, and check if it is comma delimited or not. This is going to be tricky part. You could build a regular expression, that will check each line of the file and and tell you if it is comma delimited or not.

Regular expressions are a bit hard to learn at the beginning but it should pay back after some time.

回答2:

Here's a quick Console app that will take a directory, scan the directory for all files, then iterate through them and return a percentage of lines containing commas -vs- the total lines in the file. As has been pointed out, there are CSV libraries you can validate against. This is just a quick example to get you started.

To use this, create a new Console App project in Visual Studio and name it "TestStub" then copy and past this into the "Program.cs" file.

namespace TestStub
{
    using System;
    using System.IO;
    using System.Text;

    public class Program
    {
        private static char[] CSV = { ',', ',' };
        private static bool csvFound = false;
        /// <summary>
        /// This is the console program entry point
        /// </summary>
        /// <param name="args">A list of any command-line args passed to this application when started</param>
        public static void Main(string[] args)
        {
            // Change this to use args[0] if you like 
            string myInitialPath = @"C:\Temp";
            string[] myListOfFiles;

            try
            {
                myListOfFiles = EnumerateFiles(myInitialPath);

                foreach (string file in myListOfFiles)
                {
                    Console.WriteLine("\nFile {0} is comprised of {1}% CSV delimited lines.",
                        file, 
                        ScanForCSV(file));
                }

                Console.WriteLine("\n\nPress any key to exit.");
                Console.ReadKey();
            }
            catch (Exception ex)
            {
                Console.WriteLine(
                    "Error processing {0} for CSV content: {1} :: {2}", 
                    myInitialPath, 
                    ex.Message, 
                    ex.InnerException.Message);
            }
        }

        /// <summary>
        /// Get a list of all files for the specified path
        /// </summary>
        /// <param name="path">Directory path</param>
        /// <returns>String array of files (with full path)</returns>
        public static string[] EnumerateFiles(string path)
        {
            string[] arrItems = new string[1];

            try
            {
                arrItems = Directory.GetFiles(path);
                return arrItems;
            }
            catch (Exception ex)
            {
                throw new System.IO.IOException("EnumerateFilesAndFolders() encountered an error:", ex);
            }
        }
        /// <summary>
        /// Determines if the supplied file has comma separated values
        /// </summary>
        /// <param name="filename">Path and filename</param>
        /// <returns>Percentage of lines containing CSV elements -vs- those without</returns>
        public static float ScanForCSV(string filename)
        {
            //
            // NOTE: You should look into one of the many CSV libraries
            // available. This method will not carefully scruitinize
            // the file to see if there's a combination of delimeters or
            // even if it's a plain-text (e.g. a newspaper article)
            // It just looks for the presence of commas on multiple lines
            // and calculates a percentage of them with and without
            //
            float totalLines = 0;
            float linesCSV = 0;

            try
            {
                using (StreamReader sReader = new StreamReader(filename))
                {
                    int elements = 0;
                    string line = string.Empty;
                    string[] parsed = new string[1];

                    while (!sReader.EndOfStream)
                    {
                        ++totalLines;
                        line = sReader.ReadLine();
                        parsed = line.Split(CSV);
                        elements = parsed.Length;
                        if (elements > 1)
                        {
                            ++linesCSV;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                throw new System.IO.IOException(string.Format("Problem accessing [{0}]: {1}", filename, ex.Message), ex);
            }
            return (float)((linesCSV / totalLines) * 100);
        }
    }  
}

}