正则表达式允许字符串仅包含数字 0 - 9 并将长度限制为 45
我正在尝试创建一个正则表达式，使字符串仅包含 0-9 作为字符，并且长度必须至少为 1 个字符且不超过 45。例如，00303039 会匹配，而 039330a29 则不会。
到目前为止，这就是我所拥有的，但我不确定它是否正确，
[0-9]{1,45}
我也尝试过，
^[0-9]{45}*$
但这似乎也不起作用。我对正则表达式不太熟悉，所以任何帮助都会很棒。谢谢！
I am trying to create a regex to have a string only contain 0-9 as the characters and it must be at least 1 char in length and no more than 45. so example would be 00303039 would be a match, and 039330a29 would not.
So far this is what I have but I am not sure that it is correct
[0-9]{1,45}
I have also tried
^[0-9]{45}*$
but that does not seem to work either. I am not very familiar with regex so any help would be great. Thanks!
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快到了，您所需要的只是开始锚点 (
^) 和结束锚点 ($)：\d是字符类的缩写<代码>[0-9]。您可以将其用作：锚点强制模式匹配整个输入，而不仅仅是其中的部分。
您的正则表达式
[0-9]{1,45}查找 1 到 45 位数字，因此像foo1这样的字符串也会匹配，因为它包含1。^[0-9]{1,45}查找 1 到 45 位数字，但这些数字必须位于输入的开头。它匹配123但也匹配123foo[0-9]{1,45}$查找 1 到 45 位数字，但这些数字必须位于输入的结束。它匹配123但也匹配foo123^[0-9]{1,45}$查找 1 到 45 位数字，但这些数字必须是两者在输入的开始和结束处，实际上应该是整个输入。You are almost there, all you need is start anchor (
^) and end anchor ($):\dis short for the character class[0-9]. You can use that as:The anchors force the pattern to match entire input, not just a part of it.
Your regex
[0-9]{1,45}looks for 1 to 45 digits, so string likefoo1also get matched as it contains1.^[0-9]{1,45}looks for 1 to 45 digits but these digits must be at the beginning of the input. It matches123but also123foo[0-9]{1,45}$looks for 1 to 45 digits but these digits must be at the end of the input. It matches123but alsofoo123^[0-9]{1,45}$looks for 1 to 45 digits but these digits must be both at the start and at the end of the input, effectively it should be entire input.第一个匹配字符串中任意数量的数字（也允许其他字符，即：“039330a29”）。第二个仅允许 45 位数字（且不少于）。因此，只需取两者的优点即可：
其中
\d与[0-9]相同。The first matches any number of digits within your string (allows other characters too, i.e.: "039330a29"). The second allows only 45 digits (and not less). So just take the better from both:
where
\dis the same like[0-9].如果您不想从零开始，请使用此正则表达式：
如果您不介意从零开始，请使用：
Use this regular expression if you don't want to start with zero:
If you don't mind starting with zero, use:
您可能需要两种尝试的组合：
A combination of both attempts is probably what you need:
codaddict 提供了正确的答案。至于你所尝试的，我将解释为什么他们没有成功：
[0-9]{1,45}几乎就在那里，但它匹配 1 - 至 45 位数字的字符串即使它出现在另一个包含其他字符的较长字符串中。因此，您需要^和$将其限制为完全匹配。^[0-9]{45}*$匹配精确的 45 位数字字符串，重复 0 次或任意次数 (*)。这意味着字符串的长度只能是 0 或 45 的倍数（90、135、180...）。codaddict has provided the right answer. As for what you've tried, I'll explain why they don't make the cut:
[0-9]{1,45}is almost there, however it matches a 1-to-45-digit string even if it occurs within another longer string containing other characters. Hence you need^and$to restrict it to an exact match.^[0-9]{45}*$matches an exactly-45-digit string, repeated 0 or any number of times (*). That means the length of the string can only be 0 or a multiple of 45 (90, 135, 180...).^[0-9]{1,45}$正确。^[0-9]{1,45}$is correct.出于某些安全原因，Rails 不喜欢使用 ^ 和 $ ，可能最好使用 \A 和 \z 来设置字符串的开头和结尾
Rails doesnt like the using of ^ and $ for some security reasons , probably its better to use \A and \z to set the beginning and the end of the string
对于这种情况，也可以使用单词边界 (\b) 代替起始锚点 (^) 和结束锚点 ($)：
\b是 \w 和\W（非单词字符），或位于字符串的开头或结尾。For this case word boundary (\b) can also be used instead of start anchor (^) and end anchor ($):
\bis a position between \w and \W (non-word char), or at the beginning or end of a string.