Actionscript if / else syntax Question

问题:

Which of the following best translates the English statement "If it's rainy, we will watch a movie. Otherwise we will go to the park."

   a. if (rainy = true) { gotoAndStop ("movie"); }
   b. if (rainy == true) { gotoAndStop ("movie"); }
   c. if (rainy = true) { gotoAndStop ("movie"); } else { gotoAndStop ("park"); }
   d. if (rainy == true) { gotoAndStop ("movie"); } else { gotoAndStop ("park"); }

My answer would be "d" - is that correct?

回答1:

Yes, 'd' is the correct answer.

The difference between = and == is that == compares and returns a Boolean (true or false) which you operate upon (called 'branching').

= is called the assignment operator and while perfectly valid code to write, is not what you normally want to use in an if statement.

if(x = 5) {
    doStuff();
} 

Basically means "put 5 instead of x; if x is non-zero call doStuff".

Another thing to note is when it comes to booleans, it's "safer" to write

if (rainy) {
    gotoAndStop("movie");
} else {
    gotoAndStop("park);
}

回答2:

This is cool too:

gotoAndStop(rainy ? "movie" : "park");

回答3:

or...try this, does the same.... but looks sexy :)

var activity:String = (rainy) ? "movie": "park";
gotoAndStop(activity);