How to convert extended characters in html to html code using C# Dot Net

Description: Cases where extended characters are not identified by their browser, we need to use their HTML equivalent code.

We can convert extended characters to their html equivalent code using ConvertExtendedCharactersToHtmlCode() mentioned in blog so that they will not appear as junk characters in browser.

The extended ASCII codes (character code 128-255)

Examples:

DEC	OCT	HEX	BIN	Symbol	HTML Number	HTML Name	Description
128	200	80	10000000	€	€	€	Euro sign
129	201	81	10000001
130	202	82	10000010	‚	‚	‚	Single low-9 quotation mark
131	203	83	10000011	ƒ	ƒ	ƒ	Latin small letter f with hook
132	204	84	10000100	„	„	„	Double low-9 quotation mark
133	205	85	10000101	…	…	…	Horizontal ellipsis
134	206	86	10000110	†	†	†	Dagger
135	207	87	10000111	‡	‡	‡	Double dagger

Complete list is available on http://www.ascii-code.com/

Methods:

1)   ConvertExtendedCharactersToHtmlCode()

Parameters: HtmlString => is HTml String of html file.

public static string ConvertExtendedCharactersToHtmlCode(string HtmlString)

        { 

            try

            {

                Regex r = new Regex(@"[a-zA-Z0-9<>~!@#–%^&*()—ùú_+-=`,./? ""\|}{\]\[]", RegexOptions.None);

                string SpecialCharacters = r.Replace(HtmlString, string.Empty);

                StringBuilder sb = new StringBuilder(SpecialCharacters);

                for (int i = 0; i < sb.Length; i++)

                {

                    int c = (int)sb[i];

                    if (c >= 176 && c <= 254) //Junk characters handling

                    {

                        HtmlString = HtmlString.Replace(sb[i].ToString(), "&#" + c + ";");

                    }

                    else

                    {

                        if (c == 61600 || c == 61478 || c == 61475 || c == 61488 || c == 61499 || c == 61537) // Removed for bug no. || c == 61560)

                        {

                            HtmlString = HtmlString.Replace(sb[i].ToString(), " ");

                        }

                        else if (c >= 128) //Junk characters handling

                        {

                            HtmlString = HtmlString.Replace(sb[i].ToString(), "&#" + c + ";");

                        }

                    }

                }                          

            }

            catch (Exception ex)

            {

                //throw ex;

            }

            return HtmlString;

        }