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This forum is locked: you cannot post, reply to, or edit topics. General Coding and Design => Calculator Programming
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Newbie


Bandwidth Hog


Joined: 23 Jan 2004
Posts: 2247

Posted: 13 Nov 2009 12:51:35 pm    Post subject:

This code is weird. I want it to remove any characters from a string that is not A-Z or 0-9

It does it's job unless you add a bunch of commas to at the end of a string and then it won't delete all of them.

Add a string like: Th,is,,is, a ,string.,,,,,,,,

It will delete the commas in the sentence but not at the end. Why?


Code:
        for (int position = 0; position <= strEditedPlot.Length - 1; position++)
        {
            // Convert to ascii character to compare value

            int ascii = Convert.ToInt16(char.Parse(strEditedPlot.Substring(position, 1)));

            if (ascii <= 58 && ascii >= 33 || ascii <= 25 && ascii >= 16)
            {
                strEditedPlot = strEditedPlot.Remove(position, 1);
            }
        }
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benryves


Active Member


Joined: 23 Feb 2006
Posts: 564

Posted: 13 Nov 2009 02:20:23 pm    Post subject:

That code is rather oddly written, to put it politely. Wink To retrieve a character at a particular position in a string, use the indexer (strEditedPlot[position]). Don't convert characters to ASCII then compare against magic numbers - someChar >= 'A' && someChar <= 'Z' would work instead, for example. It would also be more efficient (not to mention easier to read) to check characters one by one and, if they pass, append them to new string in a StringBuilder rather than removing them from the old string. Strings in .NET are immutable (="cannot be changed") so whenever you modify one it creates a new copy of it. StringBuilders are mutable, however.

In any case, using a regular expression would make this all a lot simpler!


Code:
strEditedPlot = new Regex("[^A-Z0-9]").Replace(strEditedPlot, "");

Character groups are put in square brackets, and a ^ at the start of a group inverts it, so that code reads as "replace any character that is not in the range A-Z or 0-9 with the empty string".


Last edited by Guest on 13 Nov 2009 02:21:22 pm; edited 1 time in total
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Newbie


Bandwidth Hog


Joined: 23 Jan 2004
Posts: 2247

Posted: 13 Nov 2009 02:27:57 pm    Post subject:

Thanks.


Didn't know that Regex existed and thus why I didn't use it. I guess if your not familiar with every namespace it can be easy to overlook something.


Last edited by Guest on 13 Nov 2009 02:30:42 pm; edited 1 time in total
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