如何从ActionScripts3中的字符串中删除单词"null"

Question

我有代码将每个2个数字转换为特定字符,此代码有效,但输出带有不需要的单词"null".我想删除它.我无法确定哪部分代码是错误的.

var encoded_numbers:String = "102030";
var sub:String;
var decode_string:String;

for (var i2:int = 0; i2 < encoded_numbers.length; i2 += 2) 
{
    sub = encoded_numbers.charAt(i2) + encoded_numbers.charAt(i2 + 1);
    //trace(sub);

    switch(sub) 
   { 
    case "10": 
        decode_string += "A";
        break; 
    case "20": 
        decode_string += "B";
        break; 
    case "30": 
        decode_string += "C";
        break; 

   }

}
trace(decode_string);//convert      

输出字符串:

nullABC

Answer 1

您的decode_string的初始值为null.只需分配初始值如下:

var decodeString:String = "";