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 $randstring;
我做错了什么?
当前回答
具体回答这个问题，有两个问题:
当你回显$randstring时，它不在作用域内。 字符在循环中没有连接在一起。
以下是更正后的代码片段:
function generateRandomString($length = 10) {
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$charactersLength = strlen($characters);
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[random_int(0, $charactersLength - 1)];
}
return $randomString;
}
用下面的调用输出随机字符串:
// Echo the random string.
// Optionally, you can give it a desired string length.
echo generateRandomString();
请注意，这个答案的以前版本使用rand()而不是random_int()，因此生成可预测的随机字符串。因此，根据这个答案的建议，它被更改为更安全。
其他回答
具有上面讨论的一些函数的类。
$options['numeric'] = true;
$options['uppercase'] = true;
$options['lowercase'] = true;
$new = new RandomString($options);
class RandomString
{
/**
* @var array
*/
private $default = ['numeric' => true, 'uppercase' => true, 'lowercase' => true];
/**
* @var array
*/
private $options;
/**
* array
*/
private $whitelist = ['numeric', 'uppercase', 'lowercase'];
/**
* RandomString constructor.
*
* @param array $options
*/
public function __construct(array $options = [])
{
$this->options = $this->default;
if(!empty($options))
{
$options = array_intersect_key($options, array_flip($this->whitelist));
if(empty($options))
{
$this->options = $this->default;
}else
{
$this->options = $options;
}
}
}
/**
* @return string
*/
private function returnCharacters(){
$options = $this->options;
$numbers = '0123456789';
$uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$lowercase = "abcdefghijklmnopqrstuvwxyz";
$characters = '';
if(isset($options['numeric']) && $options['numeric'] === true){
$characters .= $numbers;
}
if(isset($options['uppercase']) && $options['uppercase'] === true){
$characters .= $uppercase;
}
if(isset($options['lowercase']) && $options['lowercase'] === true){
$characters .= $lowercase;
}
return $characters;
}
/**
* @param $length
* @param $quantity
* @return string
*/
public function randomString($length, $quantity) {
$string = '';
$characters = $this->returnCharacters();
for ($j = 0; $j < $quantity; $j++) {
for($i = 0; $i < $length; $i++){
$string .= $characters[mt_rand(0, strlen($characters) - 1)];
}
$string .= "\n";
}
return $string;
}
/**
* @return array
*/
public function getOptions()
{
return $this->options;
}
/**
* @return mixed
*/
public function getWhitelist()
{
return $this->whitelist;
}
具体回答这个问题，有两个问题:
当你回显$randstring时，它不在作用域内。 字符在循环中没有连接在一起。
以下是更正后的代码片段:
function generateRandomString($length = 10) {
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$charactersLength = strlen($characters);
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[random_int(0, $charactersLength - 1)];
}
return $randomString;
}
用下面的调用输出随机字符串:
// Echo the random string.
// Optionally, you can give it a desired string length.
echo generateRandomString();
请注意，这个答案的以前版本使用rand()而不是random_int()，因此生成可预测的随机字符串。因此，根据这个答案的建议，它被更改为更安全。
如果您在用户可能看到或使用它的地方使用这个随机字符串(例如作为密码生成器)，您可能希望限制用于排除元音的字符集。这样你就不会不小心说脏话，也不会冒犯别人。别笑，这是常有的事。
只使用PHP本地函数的参数化一行程序，从PHP 5.1.0开始工作
str_shuffle(implode('', (array_intersect_key(($map = array_map('chr', array_merge(array_map('mt_rand', array_fill(0, $length = 25, 48), array_fill(0,$length,57)),array_map('mt_rand', array_fill(0, $length, 65), array_fill(0,$length,90)),array_map('mt_rand', array_fill(0, $length, 97), array_fill(0,$length,122))))), array_flip($keys = array_rand($map, $length))))))
一个完整的解决方案(课程加测试)，部分基于上面的一些建议…
class TokenFactory
{
private const LENGTH = 12;
private const ALLOWED = '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ~!@#$%^&*{}';
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!
