是否在新的Mailmessage正文中声明？

Question

Quick question about new MailMessage body that I cant seem to find an answer to in google.

How can I make an if statement that checks if an element is visible and then takes the string in the element and applies it to the body?

mail.Body += "<b>" + D1ContactPanel.Visible ? "Subsidiary contacts: " : "" + "</b> " + D1ContactPanel.Visible ? D1ContactDDL.Text : "" + "</br></br>";

Edit: Visual studio says "Cannot implicitly convert type 'string' to 'bool'"

Answer 1

Enclose in brackets, like:

mail.Body += "<b>" + (D1ContactPanel.Visible ? "Subsidiary contacts: " : "") + "</b> " + (D1ContactPanel.Visible ? D1ContactDDL.Text : "") + "</br></br>";

This will evaluate your condition and return appropriate string as a result which will be concatenated.

If you miss out brackets, then it first tries to concatenate D1ContactPanel.Visible to "<b>" and then evaluate the condition which fails because it cannot evaluate the string. Hence the error "cannot convert string to boolean".

Answer 2

您需要添加一些括号，不仅为了进行编译，还为了开发人员的见解:)

mail.Body += "<b>" + (D1ContactPanel.Visible ? "Subsidiary contacts: " : "") + "</b> " + (D1ContactPanel.Visible ? D1ContactDDL.Text : "") + "</br></br>";

Answer 3

mail.Body += "<b>" + (D1ContactPanel.Visible ? "Subsidiary contacts: " : "") + "</b> " + (D1ContactPanel.Visible ? D1ContactDDL.Text : "") + "</br></br>";

Answer 4

Separate the string values from your boolean condition:

mail.Body += @"<b>" + (D1ContactPanel.Visible ? "Subsidiary contacts: " : "") 
+ "</b> " + (D1ContactPanel.Visible ? D1ContactDDL.Text : "") 
+ "</br></br>";

Answer 5

Please, change your code from

mail.Body += "<b>" + D1ContactPanel.Visible ? "Subsidiary contacts: " : "" + "</b> " + D1ContactPanel.Visible ? D1ContactDDL.Text : "" + "</br></br>";

to

mail.Body += "<b>" + (D1ContactPanel.Visible ? "Subsidiary contacts: " : "" )+ "</b> " + (D1ContactPanel.Visible ? D1ContactDDL.Text : "") + "</br></br>";

Answer 6

you can Enclose in brackets like other answers to avoid exception, but I think you don't need to check two times and make this code more readable as below

if(D1ContactPanel.Visible)
   mail.Body += string.Format("<b>Subsidiary contacts: </b>{0}</br></br>", D1ContactDDL.Text);

then you can even move this string literals to constants or resources

Answer 7

你可以试试

mail.Body += string.Format("<b>{0}</b> {1}<br /><br />", D1ContactPanel.Visible ? "Subsidiary contacts: " : string.Empty, D1ContactPanel.Visible ? D1ContactDDL.Text : string.Empty);