Question

如果字符串为空，我想跳过一行。

我这样试试：

public void ReadPostedData()
{
    Sender = HttpContext.Current.Request.Form["MailFormSubmitter_sender"];
    Subject = HttpContext.Current.Request.Form["MailFormSubmitter_subject"];        
    Message = HttpContext.Current.Request.Form["Message"];
    PdfMessage = HttpContext.Current.Request.Form["PdfMessage"];

    string IsCheckPDfMailSubmit = HttpContext.Current.Request.Form["IsCheckedPDFMailForm"];
    if (IsCheckPDfMailSubmit == null || IsCheckPDfMailSubmit.Length == 0)

        //string.IsNullOrEmpty(IsCheckPDfMailSubmit);

    return IsCheckPDfMailSubmit == null;

    IsCheckedPDFMailForm = IsCheckPDfMailSubmit.Equals("True", StringComparison.OrdinalIgnoreCase); 

    string v = HttpContext.Current.Request.Form["MailFormSubmitter_includeoverviewpdf"];
    IncludeOverviewPdf = v.Equals("true,false", StringComparison.Ordinal) ? true : false;
    // http://forums.asp.net/t/1314753.aspx

    ApplicantMailNodeSelectors[0] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress1"];
    ApplicantMailNodeSelectors[1] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress2"];
    ApplicantMailNodeSelectors[2] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress3"];
}

关于这一行：

if (IsCheckPDfMailSubmit == null || IsCheckPDfMailSubmit.Length == 0)

如果为null，则不执行此行：

IsCheckedPDFMailForm = IsCheckPDfMailSubmit.Equals("True", StringComparison.OrdinalIgnoreCase);

我这样试试：

return IsCheckPDfMailSubmit == null;

但后来我收到以下错误：

错误6由于'Seneca.SfsLib.Connectors.MailFormSubmitterModel.ReadPostedData（）'返回void，因此返回关键字后面不能包含对象表达式

那么如何跳过它？

Answer 1

如果要根据if语句中的条件退出函数，当方法具有return;作为返回类型时，只使用void：

if (IsCheckPDfMailSubmit == null || IsCheckPDfMailSubmit.Length == 0) {
  return;
}

或者，不是退出函数的midde，而是可以反转条件并将其余代码放在if语句中：

if (!(IsCheckPDfMailSubmit == null || IsCheckPDfMailSubmit.Length == 0)) {
  // ...
  // rest of the code in the method
  // ...
}

如果您只想跳过以下行但是继续使用方法中的其余代码，请反转条件并将该行放在if语句中：

if (!(IsCheckPDfMailSubmit == null || IsCheckPDfMailSubmit.Length == 0)) {
  IsCheckedPDFMailForm = IsCheckPDfMailSubmit.Equals("True", StringComparison.OrdinalIgnoreCase); 
}

Answer 2

您的方法是无效类型，因此您无法返回任何值。表达式return IsCheckPDfMailSubmit == null;尝试返回bool不正确，因此会出现编译错误。

您可以通过多种方式解决，一种方法是更改if条件以检查备用案例。

public void ReadPostedData()
{
    Sender = HttpContext.Current.Request.Form["MailFormSubmitter_sender"];
    Subject = HttpContext.Current.Request.Form["MailFormSubmitter_subject"];        
    Message = HttpContext.Current.Request.Form["Message"];
    PdfMessage = HttpContext.Current.Request.Form["PdfMessage"];

    string IsCheckPDfMailSubmit = HttpContext.Current.Request.Form["IsCheckedPDFMailForm"];
    if (IsCheckPDfMailSubmit != null && IsCheckPDfMailSubmit.Length > 0)
    // A better option is to use string.IsNullOrEmpty:
    // if (!string.IsNullOrEmpty(IsCheckPDfMailSubmit))
    {

    IsCheckedPDFMailForm = IsCheckPDfMailSubmit.Equals("True", StringComparison.OrdinalIgnoreCase); 





    string v = HttpContext.Current.Request.Form["MailFormSubmitter_includeoverviewpdf"];
    IncludeOverviewPdf = v.Equals("true,false", StringComparison.Ordinal) ? true : false;
    // http://forums.asp.net/t/1314753.aspx

    ApplicantMailNodeSelectors[0] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress1"];
    ApplicantMailNodeSelectors[1] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress2"];
    ApplicantMailNodeSelectors[2] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress3"];
   }
}

Answer 3

public void ReadPostedData()
{
    Sender = HttpContext.Current.Request.Form["MailFormSubmitter_sender"];
    Subject = HttpContext.Current.Request.Form["MailFormSubmitter_subject"];        
    Message = HttpContext.Current.Request.Form["Message"];
    PdfMessage = HttpContext.Current.Request.Form["PdfMessage"];

    string IsCheckPDfMailSubmit = HttpContext.Current.Request.Form["IsCheckedPDFMailForm"];
    if (IsCheckPDfMailSubmit != null) {
        if(IsCheckPDfMailSubmit.Length > 0){
            IsCheckedPDFMailForm = IsCheckPDfMailSubmit.Equals("True", StringComparison.OrdinalIgnoreCase); 
        }
    }





    string v = HttpContext.Current.Request.Form["MailFormSubmitter_includeoverviewpdf"];
    IncludeOverviewPdf = v.Equals("true,false", StringComparison.Ordinal) ? true : false;
// http://forums.asp.net/t/1314753.aspx

    ApplicantMailNodeSelectors[0] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress1"];
    ApplicantMailNodeSelectors[1] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress2"];
    ApplicantMailNodeSelectors[2] = HttpContext.Current.Request.Form["MailFormSubmitter_applicantemailaddress3"];
}

如果字符串为空，则跳过行

3 个答案: