/*字典 Dictionary類*/
function Dictionary() {
 this.add = add;
 this.datastore = new Array();
 this.find = find;
 this.remove = remove;
 this.showAll = showAll;
 this.count = count;
 this.clear = clear;
}
function add(key, value) {
 this.datastore[key] = value;
}
function find(key) {
 return this.datastore[key];
}
function remove(key) {
 delete this.datastore[key];
}
function showAll() {
 var str = "";
 for(var key in this.datastore) {
 str += key + " -> " + this.datastore[key] + "; "
 }
 console.log(str);
}
function count() {
 /*var ss = Object.keys(this.datastore).length;
 console.log("ssss "+ss);
 return Object.keys(this.datastore).length;*/
 /**/
 var n = 0;
 for(var key in Object.keys(this.datastore)) {
 ++n;
 }
 console.log(n);
 return n;
}
function clear() {
 for(var key in this.datastore) {
 delete this.datastore[key];
 }
}
var pbook = new Dictionary();
pbook.add("Mike", "723");
pbook.add("Jennifer", "987");
pbook.add("Jonathan", "666");
pbook.showAll();//Mike -> 723; Jennifer -> 987; Jonathan -> 666;
pbook.count();//3
pbook.remove("Jennifer");
//pbook.clear();
pbook.showAll();//Mike -> 723; Jonathan -> 666;
pbook.count();//2