使用正则表达式验证密码 [英] Use regular expressions to validate passwords

问题描述

我有一个密码字段，它应该符合以下条件

I have a password field which should match the following conditions

1. 应该至少有一个字母和一个数字
2. 最小长度为 5，最大长度为 20

另外，我想知道是否所有语言的正则表达式都相同?

Also, I would like to know if regular expressions are the same for all languages?

链接到开始使用正则表达式的优秀教程(假设我只有基本的了解)也很好.

Links to good tutorials to get started with Regular Expressions (assuming I have just a basic understanding) would also be nice.

谢谢

推荐答案

最小值和最大值只需使用 strlen.

The min and max just use strlen.

我将使用的一个字符和一个数字 preg_match:

The one character and one digit I would use preg_match:

$len = strlen($string);

if ($len < 5) {
     // too short
}elseif ( $len > 20) {
     // too long.
}elseif (!preg_match('#[0-9]#', $string)) {
     // does not contain a digit
}elseif (!preg_match('#[a-z]#i', $string)) {
     // does not have a character
} 

我喜欢将我的检查分成多个检查，以便我可以准确地告诉用户缺少什么.有些人更喜欢将其捆绑在一起.

I like to break mine out to multiple checks so I can tell the user exactly what is missing. Some people prefer it bundled into one.

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