我试图在PHP中创建一个随机字符串，我得到绝对没有输出:
<?php
function RandomString()
{
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$randstring = '';
for ($i = 0; $i < 10; $i++) {
$randstring = $characters[rand(0, strlen($characters))];
}
return $randstring;
}
RandomString();
echo $randstring;
我做错了什么?
当前回答
我想要特定字符和预设长度的伪随机字符串。我希望当前版本的PHP具有最高质量的伪随机性，此时它可以是v5、v6、v7或v8，并且可以使用默认配置或特殊配置。为了解决这种混乱，我在这里选取了其他几个答案，并包含了函数可用性条件。
使用。要全局使用它，给$VALID_ID_CHARS赋值你想要的字符，然后调用它:
$VALID_ID_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
$myNewRandomId = makeId(6);
function makeId($desiredLen)
{
global $VALID_ID_CHARS;
if ($desiredLen < 1) {
throw new \RangeException("Length must be a positive integer");
}
$vLen = 0;
if (function_exists('mb_strlen')) {
$vLen = mb_strlen($VALID_ID_CHARS, '8bit') - 1;
} else {
$vLen = strlen($VALID_ID_CHARS) - 1;
}
if (function_exists('random_int')) {
$pieces = [];
for ($i = 0; $i < $desiredLen; ++$i) {
$pieces[] = $VALID_ID_CHARS[random_int(0, $vLen)];
}
return implode('', $pieces);
}
if (function_exists('openssl_random_pseudo_bytes')) {
$random = openssl_random_pseudo_bytes($desiredLen);
$id = '';
for ($i = 0; $i < $desiredLen; ++$i) {
$id .= $VALID_ID_CHARS[ord($random[$i]) % $vLen];
}
return $id;
}
http_response_code(500);
die('random id generation failed. either random_int or openssl_random_pseudo_bytes is needed');
}
其他回答
以前的答案会生成不安全或难以输入的密码。
这是安全的，并且提供了用户更有可能实际使用的密码，而不是因为一些薄弱的东西而被丢弃。
// NOTE: On PHP 5.x you will need to install https://github.com/paragonie/random_compat
/**
* Generate a password that can easily be typed by users.
*
* By default, this will sacrifice strength by skipping characters that can cause
* confusion. Set $allowAmbiguous to allow these characters.
*/
static public function generatePassword($length=12, $mixedCase=true, $numericCount=2, $symbolCount=1, $allowAmbiguous=false, $allowRepeatingCharacters=false)
{
// sanity check to prevent endless loop
if ($numericCount + $symbolCount > $length) {
throw new \Exception('generatePassword(): $numericCount + $symbolCount are too high');
}
// generate a basic password with just alphabetic characters
$chars = 'qwertyupasdfghjkzxcvbnm';
if ($mixedCase) {
$chars .= 'QWERTYUPASDFGHJKZXCVBNML';
}
if ($allowAmbiguous) {
$chars .= 'iol';
if ($mixedCase) {
$chars .= 'IO';
}
}
$password = '';
foreach (range(1, $length) as $index) {
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while ($char == substr($password, -1)) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password .= $char;
}
// add numeric characters
$takenSubstitutionIndexes = [];
if ($numericCount > 0) {
$chars = '23456789';
if ($allowAmbiguous) {
$chars .= '10';
}
foreach (range(1, $numericCount) as $_) {
$index = random_int(0, strlen($password) - 1);
while (in_array($index, $takenSubstitutionIndexes)) {
$index = random_int(0, strlen($password) - 1);
}
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password[$index] = $char;
$takenSubstitutionIndexes[] = $index;
}
}
// add symbols
$chars = '!@#$%&*=+?';
if ($allowAmbiguous) {
$chars .= '^~-_()[{]};:|\\/,.\'"`<>';
}
if ($symbolCount > 0) {
foreach (range(1, $symbolCount) as $_) {
$index = random_int(0, strlen($password) - 1);
while (in_array($index, $takenSubstitutionIndexes)) {
$index = random_int(0, strlen($password) - 1);
}
$char = $chars[random_int(0, strlen($chars) - 1)];
if (!$allowRepeatingCharacters) {
while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
$char = $chars[random_int(0, strlen($chars) - 1)];
}
}
$password[$index] = $char;
$takenSubstitutionIndexes[] = $index;
}
}
return $password;
}
<?php
/**
* Creates a random string
*
* @param (int) $length
* Length in characters
* @param (array) $ranges
* (optional) Array of ranges to be used
*
* @return
* Random string
*/
function random_string($length, $ranges = array('0-9', 'a-z', 'A-Z')) {
foreach ($ranges as $r) $s .= implode(range(array_shift($r = explode('-', $r)), $r[1]));
while (strlen($s) < $length) $s .= $s;
return substr(str_shuffle($s), 0, $length);
}
// Examples:
$l = 100;
echo '<b>Default:</b> ' . random_string($l) . '<br />';
echo '<b>Lower Case only:</b> ' . random_string($l, array('a-z')) . '<br />';
echo '<b>HEX only:</b> ' . random_string($l, array('0-9', 'A-F')) . '<br />';
echo '<b>BIN only:</b> ' . random_string($l, array('0-1')) . '<br />';
/* End of file */
function rndStr($len = 64) {
$randomData = file_get_contents('/dev/urandom', false, null, 0, $len) . uniqid(mt_rand(), true);
$str = substr(str_replace(array('/','=','+'),'', base64_encode($randomData)),0,$len);
return $str;
}
下面是一个简单的单行程序，它生成一个真正的随机字符串，而不需要任何脚本级循环或使用OpenSSL库。
echo substr(str_shuffle(str_repeat('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', mt_rand(1,10))), 1, 10);
把它分解，这样参数就清楚了
// Character List to Pick from
$chrList = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
// Minimum/Maximum times to repeat character List to seed from
$chrRepeatMin = 1; // Minimum times to repeat the seed string
$chrRepeatMax = 10; // Maximum times to repeat the seed string
// Length of Random String returned
$chrRandomLength = 10;
// The ONE LINE random command with the above variables.
echo substr(str_shuffle(str_repeat($chrList, mt_rand($chrRepeatMin,$chrRepeatMax))), 1, $chrRandomLength);
此方法的工作原理是随机重复字符列表，然后打乱组合的字符串，并返回指定的字符数。
您可以进一步随机化它，通过随机化返回字符串的长度，将$chrRandomLength替换为mt_rand(8,15)(用于8到15个字符之间的随机字符串)。
该函数的编辑版本工作正常，但我发现只有一个问题:您使用了错误的字符来包含$字符，因此'字符有时是生成的随机字符串的一部分。
要解决这个问题，请更改:
$characters = ’0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ’;
to:
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
这种方法只使用包含的字符，'字符永远不会是生成的随机字符串的一部分。
