How to merge and divide two strings with some step?

Question

My task: Merge and divide two strings with some step.

For example:
text = "abcd"
key = "12"
step = 2
result = "1ab2cd"

Пример:
1) Merging strings.

Input variables:
text = "abcd"
key = "12"
step = 2

Output variables:
result = "1ab2cd"

2) Now I need to decrypt the result of string to the source data, where key. Length and step variables are known.

Input variables:
result = "1ab2cd"
key.Length = 2
step = 2

Output variables:
text = "abcd"
key = "12"

Algorithm (1) has already been implemented:

    int step, word;
    string text, key, result = string.Empty;

    Console.Write("Enter Text : ");
    text = Console.ReadLine();
    Console.Write("Enter Key : ");
    key = Console.ReadLine();
    Console.Write("Enter Step : ");
    step = int.Parse(Console.ReadLine());

    // MIX ARRAY
    word = 0;

    if (step <= text.Length)
    {
        for (int i = 0; i < key.Length; i++)
        {
            result += key.Substring(i, 1);
            for (int k = 0; k < step; k++)
            {
                try
                {
                    result += text.Substring(word, 1);
                    word++;
                }
                catch
                {
                    break;
                }
            }
        }

        if (word < text.Length)
        {
            result += text.Substring(word, (text.Length - word));
        }
    }
    Console.WriteLine("Result Text : " + result);

    // DECIPHER ARRAY

    Console.WriteLine("text: " + text);
    Console.WriteLine("key: " + key);
    Console.ReadKey();

How to implement the algorithm (2)?

Answer 1

I will write this as another code block you can merge 2 algorthym if you want. Again Think with my 4 steps.

1- Find what variables do you need?

        string key = "", text = "", result;
        int step = 0, keyLength, textLength, word = 0;

2- Take All Values

        Console.Write("Result Text : ");
        result = Console.ReadLine();
        Console.Write("Key Length: ");
        keyLength = int.Parse(Console.ReadLine());
        textLength = result.Length - keyLength;
        Console.Write("Step: ");
        step = int.Parse(Console.ReadLine());

3- Think about algorthym

4- Think about that may arise exceptions

       for (int i = 0; i < result.Length; i = word)
        {
            if (keyLength > 0)
            {
                key += result.Substring(word, 1);
                word++;
                keyLength--;
            }
            if (textLength > 0)
            {
                for (int k = 0; k < step; k++)
                {
                    try
                    {
                        text += result.Substring(word, 1);
                        word++;
                        textLength--;
                    }
                    catch
                    {
                        break;
                    }
                }
            }

        }
        Console.WriteLine("Text : " + text);
        Console.Write("Key : " + key);
        Console.ReadKey();

Answer 2

text = "abcd" 
key = "12" 
step = 2 
result = "1ab2cd"

First ->Think about variables. How many and which kind of variable are your need.

    int step,word;
    string text,key,result;

Second ->Fill variables with needed values

    Console.Write("Enter Text : ")
    text = Console.ReadLine();
    Console.Write("Enter Key : ")
    key = Console.ReadLine();
    Console.Write("Enter Step : ")
    step = int.Parse(Console.ReadLine());

Third ->Create an algorthym for solve this problem

Forth ->Think about what exception can be and how can you solve them

    for(int i=0;i<key.Length;i++)
    {
        result+=key.Substring(i,1);
        for(int k=0; k<step; k++)
        {
           try
           {
               result+=text.Substring(word,1);
               word++;
           }
           catch
           {
               /* This blok will break 
                  when the text variable's last part's character count lest then step. */
               break;
           }
        }
     }
        if(word < text.Length)
        {
             // if there is any text after all. Calculate how many letter left then write them
             result += text.Substring(word,(text.Length-word))
        }

Console.Write("Result Text : "+result);
Console.ReadKey();

I hope this can help to you

Answer 3

I'm sorry I can't test this. I hope it helps:

     static string Combine(string text, string key, int step)
     {
        var result = "";
        int stepCount = 0;
        for (int i = 0; i < text.Length + key.Length; i++)
        {
            if (i % step == 0)
            {
                result += key[i / step];
                stepCount++;
            }
            else
            {
                result += text[i - stepCount];
            }
        }
        return result;
    }