菜鸟问个简单的逻辑问题，求解答

Question

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>";
}
逻辑菜鸟简单的

Answer 1

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;

Answer 2

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

Answer 3

这样写也可以，可逆的前不限长度echo convert_62(999990); //4C8s
echo convert_62('4C8s', 1); //999990function 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;
}

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

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
)

Answer 8

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

Answer 9

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;
}