将数字转换为EXCEL列名的方法

用递归函数将数字转换为EXCEL中的列名，直接上代码（PHP）：

 1 //递归求解
 2 function R_NumToLetter($num)
 3 {
 4     if($num == 0)
 5     {
 6         return '';
 7     }
 8     $base = 26;
 9     $mod = (int)($num % $base);
10     $num = (int)($num / $base);
11     if($mod == 0)
12         return R_NumToLetter($num - 1).NumToLetter($base);
13     if($num == 0)
14         return NumToLetter($mod);
15     return R_NumToLetter($num).NumToLetter($mod);
16 }
17 
18 function NumToLetter($num)
19 {
20     if($num == 0)
21         return '';
22     $num = (int)$num - 1;
23     $ord_A = ord('A');
24     $chr = chr($ord_A + $num);
25     return $chr;
26 }