How to read character by character right to left?

Question

I hope and you can help me please, I have a label that shows a value in binary.

Example: "1000010101", this data, I'm reading it with an inverted for. That is, starting from right to left, the binary number is dynamic, so it will not always be the same.

Until now this is my idea, but it does not give me any value

for (int i = lbl_conversion.Text.Length; i > 0; i--)
    {
        if (st[i] == 1)
        {
            MessageBox("1");
        }
        else
        {
            MessageBox("0");
        }

    }

What I would like is to read character by character from left to right and know if it is "1" or "0" and then make a comparison, could someone support me to get that result?

Thank you.

`int i = lbl_conversion.Text.Length - 1;` please, note `-1`; `i >= 0` — Dmitry Bychenko, Nov 12 '18 at 19:14
You should be getting an exception, which should be providing you a big clue about what you're doing wrong here. — Clockwork-Muse, Nov 12 '18 at 19:14
Even if you do get this working, I'm not sure how 10 separate message boxes are useful. What are you actually trying to do with this? — crashmstr, Nov 12 '18 at 19:17
See also [C# read string from back to end](https://stackoverflow.com/q/43122807/215552) — Heretic Monkey, Nov 12 '18 at 19:18

score 2 · Accepted Answer · answered Nov 12 '18 at 19:18

Since strings are zero based, correct for loop will be

   // Note "- 1" and ">=" 
   for (int i = lbl_conversion.Text.Length - 1; i >= 0; --i)
       if (st[i] == '1') //DONE: comparing with character, not integer
       {
           MessageBox("1");
       }
       else
       {
           MessageBox("0");
       }

Or you can just Reverse the string (with a help of Linq):

   // Let's read each character in reversed order
   foreach (char c in lbl_conversion.Text.Reverse())
       MessageBox(c.ToString());

score 0 · Answer 2 · answered Nov 12 '18 at 19:43

0

just one more (similar to prev posted)

string s="10111011";
s.Reverse().ToList().ForEach(ch=>Console.WriteLine(ch=='1'?"A":"0"));

answered Nov 12 '18 at 19:43

AndrewF

33
3

score 0 · Answer 3 · answered Jun 02 '20 at 14:42

When you need read the string to right to left, typically you know the number of character to have to read.

I have this function.

 private string GetValue(string strValor, int lenght)
    {
        if (strValor.Length > lenght)
            return strValor.Substring(strValor.Length - lenght, lenght);
        return strValor;
    }

strValor: String to read.
lenght: Number of character to read.

Example: GetValue("R6C5736423792", 10); return "5736423792"

How to read character by character right to left?

3 Answers3