对象引用未设置为foreach循环中C＃中对象的实例？

Question

foreach (HtmlNode link in doc.DocumentNode.SelectNodes("//a[@href]"))
{
//Code
}

this is my code where i get the exception please help me in sugesting me a solution

Thanks in advance..........

Answer 1

First stop... run the debugger and see if doc or doc.DocumentNode is null. If not, then I would check your variable instances inside the loop, including link .

Always try debugging before asking questions...

Answer 2

make sure that doc or DocumentNode isn't null.

you can wrap your code like this.

if (doc!=null && doc.DocumentNode!=null)
{
     foreach (HtmlNode link in doc.DocumentNode.SelectNodes("//a[@href]"))
      {

      }
}

Answer 3

尝试doc.DocumentNode.SelectNodes("//a[@href]")返回null还是“ doc”为null 。