Question

This is a question I have come across and failed

Suppose say

string str = "wordcounter";

One can easily find the Length using str.Length

However, is it possible in C# to get the number of letters, without using any inbuilt functions like Length, SubStr etc

Answer 1

you could write a loop and increment a counter inside this loop:

int numberOfLetters = 0;
foreach (var c in str)
{
    numberOfLetters++;
}
// at this stage numberOfLetters will contain the number of letters 
// that the string contains

there is also another way:

int numberOfLetters = str.ToCharArray().Length;

there is also another, even crazier way using the SysStringByteLen function which operates on a BSTR. Strings in .NET are layed out in memory by using a 4 byte integer containing the length of the string followed by that many 2 byte UTF-16 characters representing each character. This is similar to how BSTRs are stored. So:

class Program
{
    [DllImport("oleaut32.dll")]
    static extern uint SysStringByteLen(IntPtr bstr);

    static void Main()
    {
        string str = "wordcounter";
        var bstr = Marshal.StringToBSTR(str);

        // divide by 2 because the SysStringByteLen function returns 
        // number of bytes and each character takes 2 bytes (UTF-16)
        var numberOfLetters = SysStringByteLen(bstr) / 2; 
        Console.WriteLine(numberOfLetters);
    }
}

Obviously doing something like this instead of using the built-in Length function should never be done in any real production code and the code shown here should not be taken seriously.