C# 替换字符串中的某个字符

        static string ReplaceChar(string str, char chr1, char chr2)
        {
            if (str == null || str == string.Empty)
            {
                throw new Exception("String input can not be null");
            }

            string result = "";

            for (int i = 0; i < str.Length; i++)
            {
                if (str[i]!=chr1)
                {
                    result += str[i];
                }
                else
                {
                    result += chr2;
                }
            }

            return result;
        }

        static string ReplaceChar2(string str, char chr1, char chr2)
        {
            if (str == null || str == string.Empty)
            {
                throw new Exception("String input can not be null");
            }

            char[] chrArray = str.ToCharArray();
            string result = "";
            for (int i = 0; i < chrArray.Length; i++)
            {
                if (chrArray[i] == chr1)
                {
                    chrArray[i] = chr2;
                }
            }

            foreach (char item in chrArray)
            {
                result += item;
            }
            return result;
        }