I have RTRIM; how to make LTRIM with regexp

问题

I have RTRIM; how to make LTRIM one?

public static function rtrim(string:String):String
{
return string.replace(/\s+$/,"");
}

回答1:

Wow, seriously? You're using regular expressions to remove a constant sequence of characters from the ends of a string? Really? I don't know Actionscript/Flex, but this isn't the way to go. After a quick google I found a solution which may or may not be more efficient.

回答2:

public static function ltrim(string:String):String {
    return string.replace(/^\s+/,"");
}

Caveat: Untested! Look up the flex 3.0 documentation here. This is exactly similar to what you have, except that we use a different metacharacter to specify that we want to start searching for whitespaces (\s -- another metacharacter) from the begining(^) instead of from the end($). The + after \s tells the pattern matches to grok one or more whitespaces.

回答3:

Instead of re-inventing the wheel, why not just use the StringUtil class from Adobe's as3corelib library?

Out of interest, as3corelib defines it's trim functions as follows:

public static function trim(input:String):String
{
    return StringUtil.ltrim(StringUtil.rtrim(input));
}

public static function ltrim(input:String):String
{
    var size:Number = input.length;
    for(var i:Number = 0; i < size; i++)
    {
        if(input.charCodeAt(i) > 32)
        {
            return input.substring(i);
        }
    }
    return "";
}

public static function rtrim(input:String):String
{
    var size:Number = input.length;
    for(var i:Number = size; i > 0; i--)
    {
        if(input.charCodeAt(i - 1) > 32)
        {
            return input.substring(0, i);
        }
    }
    return "";
}

来源：https://stackoverflow.com/questions/556603/i-have-rtrim-how-to-make-ltrim-with-regexp

标签

actionscript-3

flex3