问题描述
我正在编写一个生成一些 Excel 文档的脚本,我需要将一个数字转换为其等效的列名.例如:
I'm working on a script that generate some Excel documents and I need to convert a number into its column name equivalent. For example:
1 => A 2 => B 27 => AA 28 => AB 14558 => UMX
我已经编写了一个算法来这样做,但我想知道是否有更简单或更快的方法来做到这一点:
I have already written an algorithm to do so, but I'd like to know whether are simpler or faster ways to do it:
function numberToColumnName($number){ $abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; $abc_len = strlen($abc); $result_len = 1; // how much characters the column's name will have $pow = 0; while( ( $pow += pow($abc_len, $result_len) ) < $number ){ $result_len++; } $result = ""; $next = false; // add each character to the result... for($i = 1; $i<=$result_len; $i++){ $index = ($number % $abc_len) - 1; // calculate the module // sometimes the index should be decreased by 1 if( $next || $next = false ){ $index--; } // this is the point that will be calculated in the next iteration $number = floor($number / strlen($abc)); // if the index is negative, convert it to positive if( $next = ($index < 0) ) { $index = $abc_len + $index; } $result = $abc[$index].$result; // concatenate the letter } return $result; }
你知道更好的方法吗?也许是为了让它更简单?还是性能改进?
Do you know a better way to do it? Maybe something to keep it simpler? or a performance improvement?
ircmaxell 的实现效果很好.但是,我要添加这个简短的内容:
ircmaxell's implementation works pretty fine. But, I'm going to add this nice short one:
function num2alpha($n) { for($r = ""; $n >= 0; $n = intval($n / 26) - 1) $r = chr($n%26 + 0x41) . $r; return $r; }
推荐答案
这是一个很好的简单递归函数(基于零索引数,意思是 0 == A、1 == B 等)...
Here's a nice simple recursive function (Based on zero indexed numbers, meaning 0 == A, 1 == B, etc)...
function getNameFromNumber($num) { $numeric = $num % 26; $letter = chr(65 + $numeric); $num2 = intval($num / 26); if ($num2 > 0) { return getNameFromNumber($num2 - 1) . $letter; } else { return $letter; } }
如果你想要一个索引(1 == A,等等):
And if you want it one indexed (1 == A, etc):
function getNameFromNumber($num) { $numeric = ($num - 1) % 26; $letter = chr(65 + $numeric); $num2 = intval(($num - 1) / 26); if ($num2 > 0) { return getNameFromNumber($num2) . $letter; } else { return $letter; } }
使用从 0 到 10000 的数字进行测试...
Tested with numbers from 0 to 10000...