C# Function that generates strings according to input

Question

Hi,

I need a C# function that takes 2 strings as an input and return an array of all possible combinations of strings.

private string[] FunctionName (string string1, string string2) 
{
  //code
}

The strings input will be in the following format:

String1 eg -> basement

String2 eg -> **a*f**a

Now what I need is all combinations of possible strings using the characters in String2 (ignoring the * symbols), and keeping them in the same character position.

Eg: baaement, baaefent, baaefena, basefent, basemena, etc

any help? :)

------EDIT------- This is not homework :) i need this function for a piece of program I am doing. The following is the code I have so far but it has some bugs :(

static List<string> combinations = new List<string>();

    static void Main(string[] args)
    {
        //include trimming of input string
        string FoundRes = "incoming";
        string AltRes = "*2*45*78";
        List<int> loc = new List<int>();
        string word = "";


        for (int i = 0; i < AltRes.Length; i++)
        {
            if (AltRes[i] != '*')
            {
                loc.Add(i);
                word += AltRes[i];
            }
        }

        generate(word);
        string[] aaa = InsertSymbol(FoundRes, loc.ToArray(), AltRes, combinations);

        Console.WriteLine("input string: " + FoundRes);
        Console.WriteLine("Substitute string: " + AltRes);

        Console.WriteLine("============Output============");


        for (int j = 0; j < aaa.Length; j++)
        {

            Console.WriteLine(aaa[j]);
        }
        Console.ReadKey();
    }//


    private static void generate(string word)
    {
        // Add this word to combination results set
        if (!combinations.Contains(word))
            combinations.Add(word);

        // If the word has only one character, break the recursion
        if (word.Length == 1)
        {
            if (!combinations.Contains(word))
                combinations.Add(word);
            return;
        }

        // Go through every position of the word
        for (int i = 0; i < word.Length; i++)
        {
            // Remove the character at the current position
            // call this method with the String
            generate(word.Substring(0, i) + word.Substring(i + 1));
        }
    }//

    private static string[] InsertSymbol(string orig, int[] loc, string alternative, List<string> Chars)
    {
        List<string> CombinationsList = new List<string>();
        string temp = "";
        for (int i = 0; i < Chars.Count; i++)
        {
            temp = orig;
            for (int j = 0; j < Chars[i].Length; j++)
            {
                string token = Chars[i];

                if (alternative.IndexOf(token[j]) == loc[j])
                {
                    temp = temp.Remove(loc[j], 1);
                    temp = temp.Insert(loc[j], token[j].ToString());

                    //     int pos = sourceSubst.IndexOf(token[j]);
                    //     sourceSubst = sourceSubst.Remove(pos, 1);
                    //     sourceSubst = sourceSubst.Insert(pos, ".");
                }
                else
                {
                    temp = temp.Remove(alternative.IndexOf(token[j]), 1);
                    temp = temp.Insert(alternative.IndexOf(token[j]), token[j].ToString());
                }
            }
            CombinationsList.Add(temp);
        }
        return CombinationsList.ToArray();
    }//
}

Answer 1

It does sound like homework. As a suggestion, I would ignore the first parameter and focus on getting all possible permutations of the second string. What's turned off, what's turned on, etc. From that list, you can easily come up with a method of swapping out characters of the first string.

On that note, I'm in the uncomfortable position of having a function ready to go but not wanting to post it because of the homework implication. I'd sure love for somebody to review it, though! And technically, there's two functions involved because I just happened to already have a generic function to generate subsets lying around.

Edit: OP says it isn't homework, so here is what I came up with. It has been refactored a bit since the claim of two functions, and I'm more than open to criticism.

using System;
using System.Collections.Generic;
using System.Text;

class Program
{
    static void Main()
    {
        string original = "phenomenal";
        string pattern = "*xo**q*t**";

        string[] replacements = StringUtility.GetReplacementStrings(original, pattern, true);

        foreach (string replacement in replacements)
            Console.WriteLine(replacement);

        Console.Read();
    }

    public static class StringUtility
    {
        public static string[] GetReplacementStrings(string original, string pattern, bool includeOriginal)
        {
            // pattern and original might not be same length
            int maxIndex = Math.Max(original.Length, pattern.Length);

            List<int> positions = GetPatternPositions(pattern, maxIndex, '*');
            List<int[]> subsets = ArrayUtility.CreateSubsets(positions.ToArray());
            List<string> replacements = GenerateReplacements(original, pattern, subsets);

            if (includeOriginal)
                replacements.Insert(0, original);

            return replacements.ToArray();
        }

        private static List<string> GenerateReplacements(string original, string pattern, List<int[]> subsets)
        {
            List<string> replacements = new List<string>();
            char[] temp = new char[original.Length];

            foreach (int[] subset in subsets)
            {
                original.CopyTo(0, temp, 0, original.Length);
                foreach (int index in subset)
                {
                    temp[index] = pattern[index];
                }

                replacements.Add(new string(temp));
            }

            return replacements;
        }

        private static List<int> GetPatternPositions(string pattern, int maxIndex, char excludeCharacter)
        {
            List<int> positions = new List<int>();

            for (int i = 0; i < maxIndex; i++)
            {
                if (pattern[i] != excludeCharacter)
                    positions.Add(i);
            }

            return positions;
        }
    }

    public static class ArrayUtility
    {
        public static List<T[]> CreateSubsets<T>(T[] originalArray)
        {
            List<T[]> subsets = new List<T[]>();

            for (int i = 0; i < originalArray.Length; i++)
            {
                int subsetCount = subsets.Count;
                subsets.Add(new T[] { originalArray[i] });

                for (int j = 0; j < subsetCount; j++)
                {
                    T[] newSubset = new T[subsets[j].Length + 1];
                    subsets[j].CopyTo(newSubset, 0);
                    newSubset[newSubset.Length - 1] = originalArray[i];
                    subsets.Add(newSubset);
                }
            }

            return subsets;
        }
    }
}

Answer 2

which password cracker do you want to program? :) how about

if string2 contains '*'

    foreach(char ch in string1)
        replace first * with ch, 
        execute FunctionName 
else  
   print string2

Answer 3

since it's hopw work I'd only suggest some way to solve the problem rather than writing the code.

if you loop the second parameter every time you hit a letter you'll have to options either use the letter from the first argument or the letter from the second. collect all these optins together with the index. keep a list of the parts from the first argument that will never change. iterate thorugh those two lists to created all the possible permutations

Answer 4

Decimal to Binary converted code is stolon copied from here.

static void Main()
{
    string string1 = "basement";
    string string2 = "**a*f**a";

    string[] result = GetCombinations(string1, string2);

    foreach (var item in result)
    {
        Console.WriteLine(item);
    }        

}

private static string[] GetCombinations(string string1, string string2)
{
    var list = new List<List<char>> { new List<char>(), new List<char>() };

    var cl = new List<char>();

    List<string> result = new List<string>();

    for (int i = 0; i < string1.Length; i++)
    {
        if (string2[i] == '*')
        {
            cl.Add(string1[i]);
        }
        else
        {
            list[0].Add(string1[i]);
            list[1].Add(string2[i]);
        }
    }

    int l = list[0].Count;

    for (int i = 0; i < (Int64)Math.Pow(2.0,l); i++)
    {
        string s = ToBinary(i, l);
        string ss = "";

        int x = 0;
        int y = 0;

        for (int I = 0; I < string1.Length; I++)
        {

            if (string2[I] == '*')
            {
                ss += cl[x].ToString();
                x++;
            }
            else
            {
                ss += (list[int.Parse(s[y].ToString())][y]);
                y++;
            }
        }
        result.Add(ss);
    }
    return result.ToArray<string>();
}

public static string ToBinary(Int64 Decimal, int width)
{
    Int64 BinaryHolder;
    char[] BinaryArray;
    string BinaryResult = "";

    while (Decimal > 0)
    {
        BinaryHolder = Decimal % 2;
        BinaryResult += BinaryHolder;
        Decimal = Decimal / 2;
    }

    BinaryArray = BinaryResult.ToCharArray();
    Array.Reverse(BinaryArray);
    BinaryResult = new string(BinaryArray);

    var d = width - BinaryResult.Length;

    if (d != 0) for (int i = 0; i < d; i++) BinaryResult = "0" + BinaryResult;

    return BinaryResult;
}