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 $randstring;
我做错了什么?
当前回答
这是一个简单的句子。您将得到至少一个小写字母、一个大写字母、一个数字和一个符号。使用random_int，这应该是密码安全的。不过，我并不认为这是安全的。我不是安全专家。
复制+粘贴:(只需将$len更改为所需的长度。)
$len=26;for ($chars = array('0123456789','abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLMNOPQRSTUVWXYZ','!@#$%^&*()_+-='),$randomString="",$i=0;$i<$len;$i++)$randomString .= substr($chars[$i%4], random_int(0,strlen($chars[$i%4])), 1);
echo $randomString;
再细分一下:
for (
$chars = array('0123456789','abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLMNOPQRSTUVWXYZ','!@#$%^&*()_+-='),
$randomString="",
$i=0;
$i<12;$i++)
$randomString .=
substr($chars[$i%4],
random_int(0, strlen($chars[$i%4])), 1);
我在循环中使用$chars[$ I %4]来选择从哪组字符中获取随机字符。它保证数组中的每一组字符都有多个字符。
它肯定可以改进(随机设置每个字符集的数量)，但对于我的目的来说已经足够好了。
其他回答
$t = array_merge(range('0', '9'), range('a', 'z'), range('A', 'Z'));
echo join('', array_map(function() use($t) { return $t[array_rand($t)]; }, range(1, 15)));
或一行程序
echo join('', array_map(function() { return substr('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', rand(0, 61), 1); }, range(1, 15)));
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 $password;
}
如果您在用户可能看到或使用它的地方使用这个随机字符串(例如作为密码生成器)，您可能希望限制用于排除元音的字符集。这样你就不会不小心说脏话，也不会冒犯别人。别笑，这是常有的事。
你可以试试这个:
<?php
function random($len){
$char = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
// ----------------------------------------------
// Number of possible combinations
// ----------------------------------------------
$pos = strlen($char);
$pos = pow($pos, $len);
echo $pos.'<br>';
// ----------------------------------------------
$total = strlen($char)-1;
$text = "";
for ($i=0; $i<$len; $i++){
$text = $text.$char[rand(0, $total)];
}
return $text;
}
$string = random(15);
echo $string;
?>
您也可以准时使用md5，但要小心。
您需要使用microtime()而不是time()函数，因为如果多个线程在同一秒内运行，则需要为所有线程获取不同的字符串。
<?php
$string = md5(microtime());
echo $string;
?>
一个完整的解决方案(课程加测试)，部分基于上面的一些建议…
class TokenFactory
{
private const LENGTH = 12;
private const ALLOWED = '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ~!@#$%^&*{}';
private const MIN_NUMBER_OF_DIGITS = 1;
private const MIN_NUMBER_OF_CAPS = 1;
private const MIN_NUMBER_OF_SPECIALS = 1;
private const MIN_NUMBER_OF_LETTERS = 1;
/**
* @return string
* @throws \Exception
*/
public function make(): string
{
$pass = $this->generateToken();
if ($this->isTokenValid($pass)) {
return $pass;
} else {
return $this->make();
}
}
/**
* @return string
* @throws \Exception
*/
private function generateToken(): string
{
$allowedCharacters = self::ALLOWED;
$token = '';
$max = mb_strlen($allowedCharacters, '8bit') - 1;
for ($i = 0; $i < self::LENGTH; ++$i) {
$token .= $allowedCharacters[random_int(0, $max)];
}
return $token;
}
/**
* @param $token
* @return bool
*/
private function isTokenValid($token): bool
{
$numberOfDigits = preg_match_all("/[0-9]/", $token);
$numberOfCaps = preg_match_all("/[A-Z]/", $token);
$numberOfSpecials = preg_match_all("/[~!@#\$%^&*{}]/", $token);
$numberOfLetters = preg_match_all("/[a-z]/", $token);
return
$numberOfDigits > self::MIN_NUMBER_OF_DIGITS
&& $numberOfCaps > self::MIN_NUMBER_OF_CAPS
&& $numberOfSpecials > self::MIN_NUMBER_OF_SPECIALS
&& $numberOfLetters > self::MIN_NUMBER_OF_LETTERS
;
}
}
class TokenFactoryTest
{
public function test_correct_syntax()
{
/**
* Arrange
*/
$length = 12;
$numberOfChecks = 1000;
/**
* Act & Assert
*/
$class = new TokenFactory();
$i = 0;
while ($i < $numberOfChecks) {
$generatedToken = $class->make();
$numberOfDigits = preg_match_all( "/[0-9]/", $generatedToken );
$numberOfCaps = preg_match_all( "/[A-Z]/", $generatedToken );
$numberOfSpecials = preg_match_all("/[~!@#\$%^&*{}]/", $generatedToken);
$numberOfLetters = preg_match_all("/[a-z]/", $generatedToken);
Assert::assertEquals($length, strlen($generatedToken));
Assert::assertTrue($numberOfDigits >= 1, 'Digit error: ' . $generatedToken);
Assert::assertTrue($numberOfCaps >= 1, 'Caps error: ' . $generatedToken);
Assert::assertTrue($numberOfSpecials >= 1, 'Specials error: ' . $generatedToken);
Assert::assertTrue($numberOfLetters >= 1, 'Letters error: ' . $generatedToken);
$i++;
}
}
}
顺便说一句，请确保在适合您需要的地方捕获该异常!
