How to use ternary operator for this statement in

问题:

int five = 5;

• when the variable five is equal to 5, write true
• when the variable five is not equal to 5, write false

How do I write a statement for this in ASP.NET using C#?

回答1:

int five = 5;
string answer = five == 5 ? "true" : "false";

I see that you want to use this to write the values out in ASP.NET, the answer string will hold your desired value, use that as you please.

回答2:

The ternary operator in just about every language works as an inline if statement:

Console.WriteLine((five == 5) ? 'true' : 'false');

(You shouldn't strictly need the inner parens, but I like to include them for clarity.)

If the boolean evaluates to true, then the entire expression is equal to the value between the ? and :. If the boolean evaluates to false, the expression equals the value after the :.

I don't believe you can include lines of code in the middle of the operator. These are simply supposed to be expressions that replace the entire operator "phrase" once the condition is evaluated.

I'm a Java guy and don't really know C#; maybe it's different. But probably not.

回答3:

You could keep it really simple. Comparing five to 5 results in a boolean, so the following is also possible:

int five = 5;
Console.WriteLine((five == 5).ToString());

The bool type's ToString() method is already designed to return "True" or "False", and if the lowercase alternative is needed, thats simple too:

int five = 5;
Console.WriteLine((five == 5).ToString().ToLower());

If you don't need it lowercased, you can actually completely eliminate the ToString as well:

int five = 5;
Console.WriteLine(five == 5);

回答4:

In ASP.NET, declarative (i.e, where the HTML goes):

<p>Is this five? <%= yourVariable == 5 ? "true" : "false"; %></p>

Or, alternatively, in code behind (i.e., where your C# code and classes are):

someTextBox.Text = yourVariable == 5 ? "true" : "false";

回答5:

Response.Write(five == 5 ? "True" : "False");

Though, for this example, I wouldn't use the ternary operator at all:

Response.Write(five == 5);

回答6:

Just to be safe, you should put your ternary expressions in parens (), because the ternary operator ?: has subtle precedence which can bite you if you aren't watching.

string answer = ( (five==5) ? ("true") : ("false") );

It's probably not important with this example, but if the ternary is part of a complex expression, precedence rules might make the compiler interpret the expression differently from what you intended.

回答7:

five==5?console.writeline('true'):console.writeline('false')

It works like this:

<if-expression> ? <code-when-if-expression-evaluates-true> : <code-when-if-expression-evaluates-false>

EDIT:

What I had probably been thkinking:

<%=five==5?'true':'false'%>

回答8:

Yet another variation:

string message = XmlConvert.ToString(5 == five);
Console.Write(message);

回答9:

Simplest thing is Console.WriteLine((five == 5).ToString());

回答10:

From @JohnK's comment use:

int five = 5;
string answer = five == 5 ? bool.TrueString : bool.FalseString;

Represents the Boolean value true/false as a string. This field is read-only. https://msdn.microsoft.com/en-us/library/system.boolean.truestring(v=vs.110).aspx

回答11:

using ternary operator statement in c# with Eval. (In aspx page)

<span><%# Eval("productname").ToString().Length<=0 ? "<label style=\"color: red;\">Notes<span></span></label>" : "<label style=\"color: blue;\">Notes<span></span></label>"%></span>