How can read a file, split the strings in it, and write the output to a hashtable in C#?

Question

I need to read file and split string into hash table in C#.

For example;

1231231 Hi this is the first entry / hi this is the second entry

Currently, I'm reading the lines in the files line by line using a StreamReader, and then I splitting every line to 3 different strings. For example, "1231231" to one string, then up to "/" sign to another string at last after "/" sign to another string.

1231231 will be the key of the hash table, and the others will be the values of the hash table. I'm stuck on this part.

Answer 1

Assuming you have fairly regular input set, you'll probably want to use a regular expression for this.

This pattern seems like what you want:

^(\d+)\s+([^/]+)\s+/\s+(.+)$

That would be:

• ^ : Anchor to start of string
• (\d+) : One or more digits
• \s+ : 1 or more whitespace characters
• ([^/]+) : 1 or more characters which do not equal '/'
• \s+/\s+ : 1 or more whitespace characters plus 1 slash and 1 or more whitespace characters
• (.+) : 1 or more of any character
• $ : Anchor to end of string

Answer 2

Using Bobby's regex..

    static void Main(string[] args)
    {
            Hashtable hashtable = new Hashtable();
            string[] fileLines = File.ReadAllLines(@"PATH\FILE.TXT");

            foreach (string line in fileLines)
            {
            var match =  Regex.Match(line, @"^(\d+)\s+([^/]+)\s+/\s+(.+)$");
            hashtable.Add(match.Groups[0].ToString(), new string[] { match.Groups[1].ToString(), match.Groups[2].ToString() });
            }
        }

The hashtable values are inserted as a string array since the key has to be unique.

Answer 3

Could be more optimal, but it'll work:

        char stringSplit = '/';
        char keySplit = ' ';
        Dictionary<string,string[]> dictionary = new Dictionary<string, string[]>(1000);
        using(StreamReader sr = new StreamReader(@"c:\somefile.txt"))
        {
            string line;
            while ((line = sr.ReadLine()) != null)
            {
                int keyIndex = line.IndexOf(keySplit);
                string key = line.Substring(0, keyIndex);
                string[] values = line.Substring(keyIndex + 1).Split(stringSplit);
                dictionary.Add(key,values);
            }
        }

Answer 4

Code to add entries to the hashtable:

Hashtable hashtable = new Hashtable(new EqualityComparer());
string[] fileLines = File.ReadAllLines(@"somePath");
foreach (var fileLine in fileLines)
{
    int indexOfSpace = fileLine.IndexOf(' ');
    int indexOfSlash = fileLine.IndexOf('/');
    string keyString = fileLine.Remove(indexOfSpace);
    string firstValue = 
             fileLine.Substring(indexOfSpace, indexOfSlash - indexOfSpace - 1);
    string secondValue = fileLine.Substring(indexOfSlash + 1);
    hashtable.Add(new Key(keyString), firstValue);
    hashtable.Add(new Key(keyString), secondValue);
}

Key class to wrap same string:

public class Key
{
    private readonly string s;

    public Key(string s)
    {
        this.s = s;
    }

    public string KeyString
    {
        get { return s; }
    }
}

Equality comparer that supplies GetHashCode functionality in order to make two keys based on same string go to the same entry in hashtable:

public class EqualityComparer : IEqualityComparer
{
    public bool Equals(object x, object y)
    {
        return ReferenceEquals(x, y);
    }

    public int GetHashCode(object obj)
    {
        return ((Key) obj).KeyString.GetHashCode();
    }
}

Answer 5

I thinks there is a misunderstanding. I have two values related with one key in hash table. For example;

23/december/2009 is the key. Wednesday and thursday are the two values of this key.

I think I need to store these two values in some struct or something with same key. Can anyone show me any solution about this problem ?