如何检查随机字符生成器的重复结果

也许是这样的事情？使用 in_array（）

$previous = array();
for ($i=0; $i<$quantity; $i++){
    $unique_found = false;
    while(!$unique_found){
        $a = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
        $b = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
        $c = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
        $d = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
        $code = "$a-$b-$c-$d";
        if(!in_array($code,$previous)){
            $unique_found = true;
            $previous[] = $code;
            echo $code .'<br>';
        }
    }
}

您要做的第一件事是将生成的所有代码保存到数组中。

$codes = array();
for ($i=0; $i<$quantity; $i++){
    $a = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
    $b = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
    $c = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
    $d = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
    $code = "$a-$b-$c-$d";
    echo $code .'<br>';
    $codes[] = $code;
}

为了检查它是否包含重复项，此答案提出了以下解决方案：

if (count($codes) == count(array_unique($codes))) {
    // array contains duplicates
}

如果您对哪个代码是重复的感兴趣，请尝试此操作。我首先对数组进行排序（以确保相等的值是连续的），然后检查两个连续的值是否相等。

sort($codes);
for ($i = 0; $i < count($codes) - 2; $i++) {
    if ($codes[$i] == $codes[$i + 1]) {
        // $codes[$i] is a duplicate
    }
}

如果你暗示你想摆脱重复项，那么它就像使用array_unique一样简单：

$codes = array_unique($codes);

$myValues = array();
for ($i=0; $i<$quantity; (if($unique){$i++;})){
 $a = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
 $b = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
 $c = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
 $d = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
 $code = "$a-$b-$c-$d";
 $unique = false;
 if(!in_array($code,$myValues)){
   $myValues[] = $code;
   echo $code .'<br>';
   $unique = true;
 }
}

您可以将代码用作数组中的键，因此重复的代码将被覆盖：

$results = array();
$quantity = 10000;
    while (count($results) < $quantity) {
       $a = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
       $b = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
       $c = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
       $d = substr(str_shuffle("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, 4);
       $code = "$a-$b-$c-$d";
       $results[$code] = $code;
    }