Asp.net cannot obtain internal content because it is not a solution to text

Today, an HTML control is dynamically generated in the background, similar to htmltablecell cell = new htmltablecell ();
Directly to cell. innerhtml = "cell html Code"; Then the page is displayed. When cell is used. controls. when add (new control () is used, the page output is: "internal content that cannot be obtained, because the content is not text ". Then I found a solution on the Internet:
Copy codeThe Code is as follows: stringbuilder sb = new stringbuilder ();
Stringwriter Sw = new stringwriter (SB );
Htmltextwriter HTW = new htmltextwriter (SW );
Cell. rendercontrol (HTW );

Finally, call response. Write (sb. tostring.