实现如A，B，C ... AA编号方案，AB，... AAA ...，类似于将数字转换radix26

问题描述

可能重复：
   Xnary（如二进制，但不同的）计数

在JavaScript中，我想实现在JavaScript中编号方案，使1是A，2 B，...... 26是Z，27是AA，28是AB .....

In JavaScript, I want to implement a numbering scheme in JavaScript so that 1 is A, 2 is B, .... 26 is Z, 27 is AA, 28 is AB .....

有关的，继承人的code：

For that, heres the code:

function convertor(n){

     var x = n-1,
         baseCharCode = "A".charCodeAt(0);

     var arr = x.toString(26).split(''),
         len = arr.length;

     return arr.map(function(val,i){
         val = parseInt(val,26);

         if( (i === 0) && ( len > 1)){
              val = val-1;
         }

         return String.fromCharCode(baseCharCode + val);
     }).join('');
}

这似乎做工精细，但任何想法去优化它，或实施它的另一种方式？

It seems to work fine, but any ideas to optimize it or another way of implementing it ?

推荐答案

这个系统类似于 Hexavigesimal （与A = 0开始），被称为双射基26（它没有0）。您可以使用标准的基础转换运算这样的转换：

This system is similar to Hexavigesimal (which starts with A = 0) and is called bijective base-26 (it has no 0). You can convert it using standard base-conversion arithmetic like this:

function toDecimal(str) {
    var decimal = 0;
    var letters = str.split(new RegExp());

    for(var i = letters.length - 1; i >= 0; i--) {
        decimal += (letters[i].charCodeAt(0) - 64) * (Math.pow(26, letters.length - (i + 1)));
    }

    return decimal;
}

从本质上讲，你从hexavigesimal转换为10进制如下。假设您有字符串AB。你有什么话是：

Essentially, you convert from hexavigesimal to base 10 as follows. Assume you have to string "AB". What you have then is:

1 0 (positions)
---
A B
+ +
| |
| +----> 2 * (26 ^ 0) +
+------> 1 * (26 ^ 1)
       = 28

它给你28

Which gives you 28.

另外一个例子：

2 1 0 (positions)
A B C
+ + +
| | |
| | +----> 3 * (26 ^ 0) +
| +------> 2 * (26 ^ 1) +
+--------> 1 * (26 ^ 2)
           = 731

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