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Logic to reduce character values

I am working on logic that reduces the value of alphanumeric List<char>. For example, A10 becomes A9 , BBA becomes BAZ , 123 becomes 122 . And yes, if the value entered is the last (e.g. A or 0 ), I have to return -

An additional overhead is that there is a variable List<char>that is supported by the user. It has characters that should be skipped. For example, if the list contains A , the value of GHB should be GGZ , not GHA .

The basis of this logic is the very simple use of reduction char, but with these conditions, I find it very complicated.

My project is in Silverlight, C # language. Below is my code, which I tried to do in 3 methods:

    List<char> lstGetDecrName(List<char> lstVal)//entry point of the value that returns decreased value
    {
        List<char> lstTmp = lstVal;
        subCheckEmpty(ref lstTmp);
        switch (lstTmp.Count)
        {
            case 0:
                lstTmp.Add('-');
                return lstTmp;
            case 1:
                if (lstTmp[0] == '-')
                {
                    return lstTmp;
                }
                break;
            case 2:
                if (lstTmp[1] == '0')
                {
                    if (lstTmp[0] == '1')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('9');
                        return lstTmp;
                    }
                    if (lstTmp[0] == 'A')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('-');
                        return lstTmp;
                    }
                }
                if (lstTmp[1] == 'A')
                {
                    if (lstTmp[0] == 'A')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('Z');
                        return lstTmp;
                    }
                }
                break;
        }
        return lstGetDecrValue(lstTmp,lstVal);
    }



    List<char> lstGetDecrValue(List<char> lstTmp,List<char> lstVal)
    {
        List<char> lstValue = new List<char>();
        switch (lstTmp.Last())
        {
            case 'A':
                lstValue = lstGetDecrTemp('Z', lstTmp, lstVal);
                break;
            case 'a':
                lstValue = lstGetDecrTemp('z', lstTmp, lstVal);
                break;
            case '0':
                lstValue = lstGetDecrTemp('9', lstTmp, lstVal);
                break;
            default:
                char tmp = (char)(lstTmp.Last() - 1);
                lstTmp.RemoveAt(lstTmp.Count - 1);
                lstTmp.Add(tmp);
                lstValue = lstTmp;
                break;
        }
        return lstValue;
    }






    List<char> lstGetDecrTemp(char chrTemp, List<char> lstTmp, List<char> lstVal)//shifting places eg unit to ten,etc.
    {
        if (lstTmp.Count == 1)
        {
            lstTmp.Clear();
            lstTmp.Add('-');
            return lstTmp;
        }
        lstTmp.RemoveAt(lstTmp.Count - 1);
        lstVal = lstGetDecrName(lstTmp);
        lstVal.Insert(lstVal.Count, chrTemp);
        return lstVal;
    }

I really need help with this. Please help me deal with this.

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5 answers

I found a solution to my answer with some other workarounds.

Calling Function:

    MyFunction()
    {
        //stuff I do before
        strValue = lstGetDecrName(strValue.ToList());//decrease value here
        if (strValue.Contains('-'))
        {
            strValue = "-";
        }
        //stuff I do after
    }

4 . 2 2 .

    List<char> lstGetDecrName(List<char> lstVal)//entry point, returns decreased value
    {
        if (lstVal.Contains('-'))
        {
            return "-".ToList();
        }
        List<char> lstTmp = lstVal;
        subCheckEmpty(ref lstTmp);
        switch (lstTmp.Count)
        {
            case 0:
                lstTmp.Add('-');
                return lstTmp;
            case 1:
                if (lstTmp[0] == '-')
                {
                    return lstTmp;
                }
                break;
            case 2:
                if (lstTmp[1] == '0')
                {
                    if (lstTmp[0] == '1')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('9');
                        return lstTmp;
                    }
                    if (lstTmp[0] == 'A')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('-');
                        return lstTmp;
                    }
                }
                if (lstTmp[1] == 'A')
                {
                    if (lstTmp[0] == 'A')
                    {
                        lstTmp.Clear();
                        lstTmp.Add('Z');
                        return lstTmp;
                    }
                }
                break;
        }

        List<char> lstValue = new List<char>();
        switch (lstTmp.Last())
        {
            case 'A':
                lstValue = lstGetDecrTemp('Z', lstTmp, lstVal);
                break;
            case 'a':
                lstValue = lstGetDecrTemp('z', lstTmp, lstVal);
                break;
            case '0':
                lstValue = lstGetDecrTemp('9', lstTmp, lstVal);
                break;
            default:
                char tmp = (char)(lstTmp.Last() - 1);
                lstTmp.RemoveAt(lstTmp.Count - 1);
                lstTmp.Add(tmp);
                subCheckEmpty(ref lstTmp);
                lstValue = lstTmp;
                break;
        }
        lstGetDecrSkipValue(lstValue);
        return lstValue;

    }


    List<char> lstGetDecrSkipValue(List<char> lstValue)
    {
        bool blnSkip = false;
        foreach (char tmpChar in lstValue)
        {
            if (lstChars.Contains(tmpChar))
            {
                blnSkip = true;
                break;
            }
        }
        if (blnSkip)
        {
            lstValue = lstGetDecrName(lstValue);
        }
        return lstValue;
    }


    void subCheckEmpty(ref List<char> lstTmp)
    {
        bool blnFirst = true;
        int i = -1;
        foreach (char tmpChar in lstTmp)
        {
            if (char.IsDigit(tmpChar) && blnFirst)
            {
                i = tmpChar == '0' ? lstTmp.IndexOf(tmpChar) : -1;
                if (tmpChar == '0')
                {
                    i = lstTmp.IndexOf(tmpChar);
                }
                blnFirst = false;
            }
        }
        if (!blnFirst && i != -1)
        {
            lstTmp.RemoveAt(i);
            subCheckEmpty(ref lstTmp);
        }
    }


    List<char> lstGetDecrTemp(char chrTemp, List<char> lstTmp, List<char> lstVal)//shifting places eg unit to ten,etc.
    {
        if (lstTmp.Count == 1)
        {
            lstTmp.Clear();
            lstTmp.Add('-');
            return lstTmp;
        }
        lstTmp.RemoveAt(lstTmp.Count - 1);
        lstVal = lstGetDecrName(lstTmp);
        lstVal.Insert(lstVal.Count, chrTemp);
        subCheckEmpty(ref lstVal);
        return lstVal;
    }
0

, , , , , Alpha Numeric. , .

- , .

. , A00, ? "A" "-". , Excel (.. ).

95% , , . "ABB" "AAY". , (, , ), , . , , , "-", , .

1 ( ):

public static string DecreaseName( string name, string exclusions )
{
    if (string.IsNullOrEmpty(name))
    {
        return name;
    }

    // Split the problem into sections (reverse order)
    List<StringBuilder> sections = new List<StringBuilder>();
    StringBuilder result = new StringBuilder(name.Length);
    bool isNumeric = char.IsNumber(name[0]);
    StringBuilder sb = new StringBuilder();
    sections.Add(sb);
    foreach (char c in name)
    {
        // If we change between alpha and number, start new string.
        if (char.IsNumber(c) != isNumeric)
        {
            isNumeric = char.IsNumber(c);
            sb = new StringBuilder();
            sections.Insert(0, sb);
        }
        sb.Append(c);
    }

    // Now process each section
    bool cascadeToNext = true;
    foreach (StringBuilder section in sections)
    {
        if (cascadeToNext)
        {
            result.Insert(0, DecrementString(section, exclusions, out cascadeToNext));
        }
        else
        {
            result.Insert(0, section);
        }
    }

    return result.ToString().Replace(" ", "");
}

Part2 ( ):

private static string DecrementString(StringBuilder section, string exclusions, out bool cascadeToNext)
{
    bool exclusionsExist = false;
    do
    {
        exclusionsExist = false;
        cascadeToNext = true;
        // Process characters in reverse
        for (int i = section.Length - 1; i >= 0 && cascadeToNext; i--)
        {
            char c = section[i];
            switch (c)
            {
                case 'A':
                    c = (i > 0) ? 'Z' : ' ';
                    cascadeToNext = (i > 0);
                    break;
                case 'a':
                    c = (i > 0) ? 'z' : ' ';
                    cascadeToNext = (i > 0);
                    break;
                case '0':
                    c = (i > 0) ? '9' : ' ';
                    cascadeToNext = (i > 0);
                    break;
                case ' ':
                    cascadeToNext = false;
                    break;
                default:
                    c = (char)(((int)c) - 1);
                    if (i == 0 && c == '0')
                    {
                        c = ' ';
                    }
                    cascadeToNext = false;
                    break;
            }
            section[i] = c;
            if (exclusions.Contains(c.ToString()))
            {
                exclusionsExist = true;
            }
        }
    } while (exclusionsExist);
    return section.ToString();
}

, , DecrementString, .

+2

, , , - , char, char 1

0

, , :

char DecrementAlphaNumericChar(char input, out bool hadToWrap)
{
    if (input == 'A')
    {
        hadToWrap = true;
        return 'Z';
    }
    else if (input == '0')
    {
        hadToWrap = true;
        return '9';
    }
    else if ((input > 'A' && input <= 'Z') || (input > '0' && input <= '9'))
    {
        hadToWrap = false;
        return (char)((int)input - 1);
    }
    throw new ArgumentException(
        "Characters must be digits or capital letters",
        "input");
}

char DecrementAvoidingProhibited(
    char input, List<char> prohibited, out bool hadToWrap)
{
    var potential = DecrementAlphaNumericChar(input, out hadToWrap);
    while (prohibited.Contains(potential))
    {
        bool temp;
        potential = DecrementAlphaNumericChar(potential, out temp);
        if (potential == input)
        {
            throw new ArgumentException(
                "A whole class of characters was prohibited",
                "prohibited");
        }
        hadToWrap |= temp;
    }
    return potential;
}

string DecrementString(string input, List<char> prohibited)
{
    char[] chrs = input.ToCharArray();
    for (int i = chrs.Length - 1; i >= 0; i--)
    {
        bool wrapped;
        chrs[i] = DecrementAvoidingProhibited(
                      chrs[i], prohibited, out wrapped);
        if (!wrapped)
            return new string(chrs);
    }
    return "-";
}

, , . A10 A09 A9. , , .

List<char> Hashset <char> s, Contains.

0

, . , , , ( ).

The main thing is to define your "alphabet" directly and indicate which characters in it are illegal and should be skipped, and then use a list or array of positions in this alphabet to determine the word you start from.

I can't spend more time on it right now, but please let me know if you decide to use it and make it work!

string[] alphabet = {a, b, c, d, e};
string[] illegal = {c, d};


public string ReduceString(string s){
            // Create a list of the alphabet-positions for each letter:
    int[] positionList = s.getCharsAsPosNrsInAlphabet();
    int[] reducedPositionList = ReduceChar(positionList, positionList.length);

    string result = "";
    foreach(int pos in reducedPositionList){
        result += alphabet[pos];
    }

    return result;
}


public string ReduceChar(string[] positionList, posToReduce){
    int reducedCharPosition = ReduceToNextLegalChar(positionList[posToReduce]);
    // put reduced char back in place:
    positionList[posToReduce] = reducedCharPosition; 

    if(reducedCharPosition < 0){
        if(posToReduce <= 0){
            // Reached the end, reduced everything, return empty array!:
            return new string[](); 
        }
        // move to back of alphabet again (ie, like the 9 in "11 - 2 = 09"):
        reducedCharPosition += alphabet.length;     
        // Recur and reduce next position (ie, like the 0 in "11 - 2 = 09"):
        return ReduceChar(positionList, posToReduce-1); 
    }

    return positionList;
}


public int ReduceToNextLegalChar(int pos){
    int nextPos = pos--;
    return (isLegalChar(nextPos) ? nextPos : ReduceToNextLegalChar(nextPos));
}


public boolean IsLegalChar(int pos){
        return (! illegal.contains(alphabet[pos]));
}
enter code here
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