Question

I need some help. Basically, I have a paragraph of text in a text file, and I need to read the textfile (stored as a string) into a List of characters and stores the amount of time they appear inside the string. So it will produce a list between (A-Z) and order it depending on how many times the characters appear. Is there a way to do this without using LINQ.

Thank you 🙂

Answer 1

An efficient and easy way is to create a ConcurrentDictionary with the char as key and the number it appears as value. It has the nice AddOrUpdate(upsert) method:

string text = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.";
var chars = new System.Collections.Concurrent.ConcurrentDictionary<char, int>();
foreach (char c in text)
{
   chars.AddOrUpdate(c, 1, (chr, count) => count + 1);
}

If you want to order it by the number without Linq(Lambda != Linq) you can use this code:

List<KeyValuePair<char, int>> charList = chars.ToList();
charList.Sort((firstPair, nextPair) =>
{
    return firstPair.Value.CompareTo(nextPair.Value);
});

Edit: If you want to order descending change above a little bit:

charList.Sort((firstPair, nextPair) =>
{
    return -(firstPair.Value.CompareTo(nextPair.Value));
});

result:

Console.Write(string.Join(Environment.NewLine, charList.Select(kv => string.Format("Char={0} Num={1}", kv.Key, kv.Value))));

Char=  Num=90
Char=e Num=59
Char=t Num=43
Char=s Num=39
Char=n Num=38
Char=i Num=32
Char=a Num=28
Char=o Num=25
Char=r Num=24
Char=p Num=18
Char=m Num=18
Char=l Num=17
Char=u Num=17
Char=d Num=16
Char=h Num=14
Char=y Num=13
Char=g Num=11
Char=c Num=10
Char=k Num=7
Char=w Num=6
Char=f Num=6
Char=I Num=6
Char=v Num=5
Char=b Num=5
Char=L Num=5
Char=, Num=4
Char=. Num=4
Char=0 Num=3
Char=x Num=2
Char=1 Num=2
Char=' Num=1
Char=5 Num=1
Char=M Num=1
Char=A Num=1
Char=P Num=1
Char=6 Num=1
Char=9 Num=1