Confused about the ?: operator

I h开发者_如何学Cave this code:

if (!codeText.StartsWith("<p>"))
{
    codeText = string.Concat("<p>", codeText, "</p>");
}

How can I make it use the ?: operator?

Since the conditional operator needs an else clause, you need to tell it to use the original value:

codeText = codeText.StartsWith("<p>") ? codeText : "<p>" + codeText + "</p>";

However, there is no point in doing this; it's just more confusing.

codeText = codeText.StartsWith("<p>") ?
               codeText :
               string.Concat("<p>", codeText, "</p>");

In this case it doesn't make much sense to use the ternary operator. I would just stick with the if statement you have now. Typically you would use the ternary operator in an assignment statement or somewhere that you can't use a typical if statement.

However, if you really want to, you could do it like this.

codeText = !codeText.StartsWith("<p>") ? string.Concat("<p>", codeText, "</p>") : codeText; 

Here's the MSDN page for the ternary operator. http://msdn.microsoft.com/en-US/library/ty67wk28%28v=VS.80%29.aspx

variable = condition ? value if condition is true : value if condition is false

codeText = (!codeText.StartsWith("<p>")?string.Concat("<p>", codeText, "</p>"):codeText);

You could do it like this:

codeText = codeText.StartsWith("<p>")
    ? codetext
    : string.Concat("<p>", codeText, "</p>");

But I'm not sure why would you do that.

Like this:

codeText = codeText.StartsWith("<p>") ? codeText : string.Concat("<p>", codeText, "</p>");

If it's fairly long, I usually write it across multiple lines like this:

codeText = codeText.StartsWith("<p>")
  ? codeText
  : string.Concat("<p>", codeText, "</p>");

although I have to admit, I don't see the benefit to using the ?: operator here, given that you don't have an else case, you're having to add one that does codeText = codeText to use it.

/*if*/ condition
     /*then*/? statement1
     /*else*/: statement2

so, basically this if construction:

if(condition){
    //statement1
}else{
    //statement2
}

can be written like :

condition 
    ? statement1
    : statement2;