菜鸟问个简单的逻辑问题，求解答

[fjufo]

我是想实现62进制的功能，可是下面这段代码只能echo出来，不能返回，不知道是什么原因，求高手解答

function dwz($id,$str=""){
	$a=array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
	$zs=(int)($id/sizeof($a));
	$xs=$id%sizeof($a);
	if($zs>=sizeof($a)){
		$str=$a[$xs].$str;
		dwz($zs,$str);
	}
	else{
		if($str==""){
			return $a[$zs].$a[$xs];
		}
		else{
			echo   $a[$zs].$str;//这里只能输出
			return $a[$zs].$str;//返回没值，不知道什么原因
		}
	}
}
for($i=999990;$i<=1000000;$i++){
	echo dwz($i);
	echo "<br>";
}

[xuzuning]

第7行 dwz($zs,$str); 没有承接返回 $str = dwz($zs,$str); 函数结束处还需要有 return $str;

[板功]

    if($zs>=sizeof($a)){
         $str=$a[$xs].$str;
         dwz($zs,$str); //这里加入return： return dwz($zs, $str);    
}
 

[fjufo]

引用 1 楼 xuzuning 的回复:

第7行 dwz($zs,$str); 没有承接返回 $str = dwz($zs,$str); 函数结束处还需要有 return $str;

哈哈，可以啦，谢谢你的提醒和指导

[xuzuning]

这样写也可以，可逆的前不限长度

echo convert_62(999990); //4C8s
echo convert_62('4C8s', 1); //999990

function convert_62($s, $mode=0) {
  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');
  $r = '';
  if($mode) {
    $d = array_flip($d);
    for($i=0; $i<strlen($s); $i++) $r = bcmul($r, '62') + $d[$s{$i}];
  }else {
    while($s) {
      $r = $d[bcmod($s, '62')] . $r;
      $s = bcdiv($s, '62');
    }
  }
  return $r;
}

[fjufo]

引用 4 楼 xuzuning 的回复:

这样写也可以，可逆的前不限长度

echo convert_62(999990); //4C8s
echo convert_62('4C8s', 1); //999990

function convert_62($s, $mode=0) {
  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');
  $r = '';
  if($mode) {
    $d = array_flip($d);
    for($i=0; $i<strlen($s); $i++) $r = bcmul($r, '62') + $d[$s{$i}];
  }else {
    while($s) {
      $r = $d[bcmod($s, '62')] . $r;
      $s = bcdiv($s, '62');
    }
  }
  return $r;
}

受用了，谢谢你

[fjufo]

引用 4 楼 xuzuning 的回复:

这样写也可以，可逆的前不限长度

echo convert_62(999990); //4C8s
echo convert_62('4C8s', 1); //999990

function convert_62($s, $mode=0) {
  $d = str_split('0123456789ABCDEFGHIJKLMNOPQRSTUVEXYZabcdefghijklmnopqrstuvwxyz');
  $r = '';
  if($mode) {
    $d = array_flip($d);
    for($i=0; $i<strlen($s); $i++) $r = bcmul($r, '62') + $d[$s{$i}];
  }else {
    while($s) {
      $r = $d[bcmod($s, '62')] . $r;
      $s = bcdiv($s, '62');
    }
  }
  return $r;
}

不好意思，请问下为什么我把这个文件放在本地测试可以用，但是放在服务器上不能用，会提示找不到bcmod这个函数

[xuzuning]

嗯，这是 php_bc 扩展没加载的原因（php for win 是自动加载的） 你还可以检查一下 php_gmp 扩展是否已加载，用这个函数库也是一样的

[fjufo]

引用 7 楼 xuzuning 的回复:

嗯，这是 php_bc 扩展没加载的原因（php for win 是自动加载的） 你还可以检查一下 php_gmp 扩展是否已加载，用这个函数库也是一样的

真的没有加载，那怎么办啊？ 我没服务器的权限

[xuzuning]

print_r(get_loaded_extensions()); 看看都有些什么

[fjufo]

引用 9 楼 xuzuning 的回复:

print_r(get_loaded_extensions()); 看看都有些什么

Array
(
    [0] => date
    [1] => libxml
    [2] => openssl
    [3] => pcre
    [4] => zlib
    [5] => ctype
    [6] => curl
    [7] => dom
    [8] => filter
    [9] => ftp
    [10] => gd
    [11] => hash
    [12] => iconv
    [13] => json
    [14] => mbstring
    [15] => mcrypt
    [16] => mhash
    [17] => mysql
    [18] => SimpleXML
    [19] => SPL
    [20] => PDO
    [21] => posix
    [22] => Reflection
    [23] => session
    [24] => pdo_sqlite
    [25] => sockets
    [26] => SQLite
    [27] => standard
    [28] => tokenizer
    [29] => xml
    [30] => xmlreader
    [31] => xmlwriter
    [32] => zip
    [33] => apache2handler
    [34] => memcache
    [35] => mssql
    [36] => soap
    [37] => Zend Optimizer
)

[xuzuning]

没权限就不好办了 就自己写吧，你不是也写了吗

[fjufo]

引用 11 楼 xuzuning 的回复:

没权限就不好办了 就自己写吧，你不是也写了吗

我写的那个有错，发现运算到后面就错了，然后就用了你的 还是没搞清楚我的那个错在哪里，为什么运算到后面就错了 大神，帮忙看下吧

[fjufo]

function dwz($id,$str=""){
$a=array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
	$zs=(int)($id/sizeof($a));
	$xs=$id%sizeof($a);
	if($zs>=sizeof($a)){
		$str=$a[$xs].$str;
		$str=dwz($zs,$str);
	}
	else{
		if($str==""){return $a[$zs].$a[$xs];}
		else{return $a[$zs].$str;}
	}
	return $str;
}

这是我根据你的提示改的，可以显示出来，但是我之前的算法有错，帮忙看下

[fjufo]

终于可以了，谢谢大神

function dwz($s) {
  $d = str_split('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVEXYZ');
  $r = '';
  while($s) {
	$r = $d[(int)($s%62)].$r;
	$s = (int)($s/62);
  }
  return $r;
}