ActionScript的for循環

actionscript支持的for循環有三種形式:

1.for(初始值;條件;遞增)

例如:

for(var x:int=1;x<=10;x++)
trace(x);

trace()會把結果輸出到日誌文件.

2.for(屬性名 in 數組/對象)

例如:

var myArray:Array = ["alpha","beta","chi"];
for(var i:String in myArray){
trace(i);
}

循環是按照屬性名迭代,而數組的屬性名是數組的索引.因此輸出結果爲:

0

1

2

能夠經過下面的方法取得值:

var myArray:Array = ["alpha","beta","chi"];
for(var i:String in myArray){
trace(myArray[i]);
}

爲何變量i在這裏是String而不是int?由於for...in循環返回的是屬性名,而屬性名是String;

若是在for...in循環中使用int,大多數狀況下回出錯.

訪問對象與數組不一樣的是,對象直接包含屬性或特性,如:

var myObject:Object = {firstName:'Jeff',lastName:'Smith'};
for(var i:String in myObject){
trace("Property:"+i+"="+myObject[i]);
}

輸出:

Property:firstName=Jeff

Property:lastName=Smith

3.for each(項 in 數組/對象)

for each...in循環用於迭代數組和對象,但測試的不是屬性名,而是屬性值

var myObject:Object = {firstName:'Jeff',lastName:'Smith'};
for each(var i:String in myObject){
trace(i);
}

輸出:

Jeff

Smith