Fastest way to get next char value in c# win. form

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Can somebody give me the fastest way to get next char value in c# win. form

example:-
Input :- a
Output :- b

Here comes the tricky part that the solution should be executed within {00:00:00.0000020} sec.

my code till now is [here i don't need next char which are comma, quotes, brackets]

private static char NextSeries(char LastChar)
{
    char NewChar = ' ';
    try
    {
        Again:
        NewChar = LastChar++;
        if(NewChar == '\'' || NewChar == '"' || NewChar == '(' || NewChar == ')' || NewChar == ',')
                {
                    LastChar = NewChar;
                    goto Again;
                }
            }
            catch (Exception ex) { }
            return NewChar;
        }

Thanks in advance

Posted 29-Oct-14 0:51am

agent_kruger

Updated 29-Oct-14 1:46am

v3

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BillWoodruff 29-Oct-14 6:55am

Are you handling only a limited range of the 256 chars possibly represented in one byte ? Like, for example, only a~z,0~9,A~Z ?

agent_kruger 29-Oct-14 7:47am

sorry sir forgot to paste full code sorry for that and please see if you can help me with my new code and i am not using 256 char but all possible char

2 solutions

Solution 1

Have you considered the postfix increment operator:

C#

char c = 'a';
Stopwatch s1 = new Stopwatch();
s1.Start();
for (int i = 0; i < 1000000; i++)
    {
    c++;
    }
s1.Stop();
Console.WriteLine(s1.ElapsedMilliseconds);

Gives me an output of "3" or "4", in the debugger, so without optimisations. Which is well and truly within your limit!
Exactly how fast it runs in your system is down to the processor speed, cores count and load at the time.

Posted 29-Oct-14 1:12am

OriginalGriff

Comments

agent_kruger 29-Oct-14 7:46am

sorry sir forgot to paste full code sorry for that and please see if you can help me with my new code

OriginalGriff 29-Oct-14 8:00am

I'm not even looking at that! "goto"? Seriously?

agent_kruger 29-Oct-14 8:01am

sir i have to call "goto" as if the char is coming which i don't need then i have to get new char.

OriginalGriff 29-Oct-14 8:51am

How long have you been programming?
Is there something wrong with a "while" loop?
And if you want speed, don't use "if": use a switch, or set up a lookup table to specify the character translation and forget the loop altogether!

agent_kruger 29-Oct-14 8:54am

look table? u mean storing all char before hand a container?

BillWoodruff 29-Oct-14 7:51am

Well, I doubt the OP needs to handle every possible character in Unicode Space from 0x0000 to 0x1F8FF, let alone a meelion (as the Register would say) :)

OriginalGriff 29-Oct-14 7:57am

Likewise, but you have to run a good number of samples in order to get even a vaguely useful number out of the timer!

agent_kruger 29-Oct-14 7:59am

sir i can't understand where you are pointing me at, can you make the statement a little simple.

BillWoodruff 29-Oct-14 8:51am

There are 129,279 (hex 0x1F8FF) possible characters in the complete Unicode Character space; most likely you'll be dealing with a very small subset of those, depending on language/encoding.

See my solution below for ideas.

cheers, Bill

agent_kruger 29-Oct-14 8:53am

can you tell me how to get "all Unicode Character" in c#?

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BillWoodruff · Accepted Answer · 2014-10-29T02:44:00

I doubt you will need to handle all the Unicode characters in the range 0x0000 to 0x1F8FF, and I think the correct strategy for getting speedy look-up here is to pre-compute the possible character output for each character input ... not to calculate, and test, character by character.

Here's a sample implementation:

C#

private Dictionary<char,> nextCharLookUp = new Dictionary<char,>();
private List<char> excludeChars;

private void buildCharLists(int startChar, int endChar)
{
    excludeChars = new List<char>
    {
        '\'','"','(',')',','
    };

    for (int i = startChar; i <= endChar; i++)
    {
        char c1 = Convert.ToChar(i);
        char c2 = Convert.ToChar(i + 1);

        // forbidden character ?
        if (excludeChars.Contains(c1)) continue;

        // c1 is valid, but, what if the next char is invalid ?
        if (excludeChars.Contains(c2))
        {
            // this may not be what you want ?
            nextCharLookUp.Add(c1,c1);
        }
        else
        {
            // just fine here ...
            nextCharLookUp.Add(c1,c2);
        }
    }
}

Obviously, if you can pre-process your file/string before parsing it to remove any characters you don't want to handle, you'll save time.

Left for you is to write some code that uses the 'nextCharLookUp Dictionary built here to parse file/string data: oh yes, you'll still have to test for "forbidden" characters, and do the right thing.

Dictionary look-up in .NET is highly optimized, i.e., fast (under-the-hood .NET Generic Dictionaries are Hash-Tables).