Letter frequencies. English text contains some letters more than others—for example, the lowercase "e" is often the most common. It is possible to compute a table of letter frequencies.

C# method. We can perform letter frequency analysis with a method in the C# language. This may be part of a project or required for simple textual analysis.

Example. The first part of the solution is declaring an array to store the frequencies. The char type is 2 bytes, which means it contains 65535 elements to store.

char Array

int Array

char

File.ReadAllText

Loop, String Chars

Console.WriteLine

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Array to store frequencies.
        int[] c = new int[(int)char.MaxValue];

        // Read entire text file.
        string s = File.ReadAllText("text.txt");

        // Iterate over each character.
        foreach (char t in s)
        {
            // Increment table.
            c[(int)t]++;
        }

        // Write all letters found.
        for (int i = 0; i < (int)char.MaxValue; i++)
        {
            if (c[i] > 0 && char.IsLetterOrDigit((char)i))
            {
                Console.WriteLine("Letter: {0}  Frequency: {1}", (char)i, c[i]);
            }
        }
    }
}
aaaa
bbbbb
aaaa
bbbbb
aaaa bbbbb
CCcc
xx
y y y y y
Z
Letter: C  Frequency: 2
Letter: Z  Frequency: 1
Letter: a  Frequency: 12
Letter: b  Frequency: 15
Letter: c  Frequency: 2
Letter: x  Frequency: 2
Letter: y  Frequency: 5

Some notes. Most important in the solution is how the array is declared and the constants are used. An array can be used to record counts.

Array

A summary. We counted the letter frequencies in a string or file. This is handy code to have for text-based processing. It can be used to determine if a string is likely English or not.