Format placeholder in string

StringExtension.cs

/// <summary>
    /// Format placeholder in string
    /// </summary>
    public static class StringExtension
    {
        public static string FormatPlaceholder(this string inString, params string[] param)
        {
            int placeholderCounter = 0;
            string[] placeholder = new string[param.Length];

            char[] inStringCharArray = inString.ToCharArray();

            for (int i = 0; i < inStringCharArray.Length; i++)
            {
                try
                {
                    // check next symbol and enlarge increment count
                    while (inStringCharArray[i] == '{')
                        if (inStringCharArray[i + 1] == '{')
                            i++;
                        else
                            break;
                        

                    if (inStringCharArray[i] == '{')
                    {
                        int startIndex = i;
                        int counter = 0;

                        // init placeholder array use static length
                        char[] placeholderCharArray = new char[20];

                        while (inStringCharArray[startIndex] != '}')
                        {
                            placeholderCharArray[counter] = inStringCharArray[startIndex];
                            counter++;
                            startIndex++;

                            // add last simbol into array
                            if (inStringCharArray[startIndex] == '}')
                                placeholderCharArray[counter] = inStringCharArray[startIndex];
                        }

                        // remove empty char and create the placeholder string
                        placeholder[placeholderCounter] = new string(placeholderCharArray).Replace("\0", "");
                        placeholderCounter++;
                    }
                }
                catch (Exception e)
                {
                    throw new ArgumentOutOfRangeException("Placeholder in string. than count params", e);
                }
            }

            try
            {
                for (int i = 0; i < param.Length; i++)
                {
                    inString = inString.Replace(placeholder[i], param[i]);
                }
            }
            catch (Exception e)
            {
                throw new ArgumentOutOfRangeException("Than count params grand placeholder in string", e);
            }

            return inString;
        }
    }