Question

How can I define a Dictionary with string key in AS3? and how to do read operation?
for example:

var Dic:Dictionary = new Dictionary();
Dic["Exhausted"] = "He who talks more is sooner exhausted, please keep smiling :)";
String str = str.substring(8,str.length-1); // == str = "Exhausted";
trace('Dic[' + str + '] = ' + Dic[str]);

the output is Dic[Exhausted] = undefined???!!

why?

Answer 1

I think you have a syntax error on this line:

String str = str.substring(8,str.length-1);

If you just use this :

var d:Dictionary = new Dictionary();
d["Exhausted"] = "He who talks more is sooner exhausted, please keep smiling :)";

trace(d["Exhausted"]);

You can see it’s all fine.

The problem with var str:String = str.substring(8,str.length-1); is that you define a String named “str”: var str:String, but you assign a value which is the result of the substring() method called on str and of cours str does not exist yet when you call substring on it.
Not sure if this makes sense: you define str as the result of applying substring on str.

The actionscript compiler should’ve complained btw:

expected a definition keyword (such as function) after attribute String, not str.

Just a wild guess, but would you happen to have str defined somewhere else in your code and you just update str again using str before using it ? In which case, you shouldn’t redefine, str, you should simply assign a new value.
e.g.

//somewhere else
var str:String = "12345678Exhausted";
//further down
var Dic:Dictionary = new Dictionary();
Dic["Exhausted"] = "He who talks more is sooner exhausted, please keep smiling :)";
str = str.substring(8,str.length); // == str = "Exhausted";
trace('Dic[' + str + '] = ' + Dic[str]);

Also, another syntax error is how you define str:
should be var str:String (as2/as3 syntax), not String str(java/c++/etc. style)