How does the ternary operator work?

Question

Please demonstrate how the ternary operator works with a regular if/else block. Example:

Boolean isValueBig = value > 100 ? true : false;

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Exact Duplicate: How do I use the ternary operator?

Solution 1

Boolean isValueBig = ( value > 100  ) ? true : false;


Boolean isValueBig;

if(  value > 100 ) { 
      isValueBig = true;
} else { 
     isValueBig = false;
}

Solution 2

The difference between the ternary operation and if/else is that the ternary expression is a statement that evaluates to a value, while if/else is not.

To use your example, changing from the use of a ternary expression to if/else you could use this statement:

Boolean isValueBig = null;
if(value > 100)
{ 
    isValueBig = true 
}
else
{
    isValueBig = false;
}

In this case, though, your statement is equivalent to this:

Boolean isValueBig = (value > 100);

Solution 3

When I was new to C++, I found that it helped to read this construct as follows:

Boolean isValueBig = if condition ? then x else: y;

(Notice that this isn't valid code. It's just what I trained myself to read in my head.)

Solution 4

I was never a fan of the ternary operator because I thought it was hard to read. As it so happens, Jon Skeet and his book, C# in Depth finally hit this old dog over the head and got it to sink in. Jon said, and I paraphrase, think of it as a question.

value > 100?

"yes" : "no"

Now the blind can see.

Hope this helps you make it second nature.

Solution 5

Boolean isValueBig;

if (value > 100)
{
   isValueBig = true;
}
else 
{
   isValueBig = false;
}

View more solutions

Comments

[Joachim Sauer]

should "Java", "C" and a lot of other language be added as well? Since they all support the ternary operator pretty much the same way.

[Andrew Hare]

Not to be too picky but "(condition) ? :" is a conditional expression in the form of a ternary operator. It is in the form of a ternary operator because it takes 3 arguments.

[abelenky]

This is valid use of the ternary operator, but a less-than-stellar-example, because the conditional-expression itself is boolean. Testing it to resolve to true/false is kinda redundant. This would be best written as: Boolean isValueBig = (value > 100);

[Brian Rasmussen]

That is a bad example of as it could more easily have been written as IsValueBig = value > 100; No need to assign bools based on an evaluation of a bool.

[Dennis Kioko]

Duplicate of: stackoverflow.com/questions/392932/….

[Andrei Rînea]

I don't mean to be annoying (there's another word for that too) but wasn't there a rule that stated that you should try and document yourself BEFORE posting a question on Stackoverflow?!

[Frederik Gheysels]

I don't want to be annoying as well, but I believe that you could have gotten the answer to that question much quicker if you just looked in the help or msdn for the ternary operator.

[WolfmanDragon]

I remember what my Java instructor told us. "Here is how you use a ternary operator .......... Now that you know what it is, don't EVER use it!" Sugar rots the best code.

[user1568901]

I can't imagine NOT using it. It's simple to read once you get used to it. Nice and short, more code stays on screen. Can insert where needed much easier. One of the best features of the C language family!

[John Kraft]

People who say not to use it do not understand it. These are, generally, the people that use it for flow control: (Condition) ? DoThis() : DoThat();

[Sampson]

You are welcome. I'm pleased to see how quickly you got responses - I love StackOverflow!

[WolfmanDragon]

I agree, although explicit casts should handle it in most cases, but it looks so ugly.

[peterchen]

Or maybe Boolean isValueBig = (( value > 100 ) ? true : false) ? true : false; to make it even more boolean – i.o.w. this is a very pointless (though correct) use of the ternary operator.

[WolfmanDragon]

Ternary is sugar anyway, and we know what sugar does to our teeth. Sugar is evil!

[Kent Fredric]

actually, in reality I'd hope you'd just use isValueBig = ( value > 100 ) ; it work the same :P

[Zach Hutchins]

"The ternary expression is a statement", the ternary expression is a expression, it expresses a value, if/else is a statement, ternary could become an expression statement but I would say by itself it is an expression, this is what makes turnery pretty powerful in my opinion.