正则表达式允许字符串只包含数字 0 - 9 并将长度限制为 45 [英] Regex allow a string to only contain numbers 0 - 9 and limit length to 45

问题描述

我正在尝试创建一个正则表达式，让字符串只包含 0-9 作为字符，并且长度必须至少为 1 个字符且不超过 45.因此，例如 00303039 将是匹配项，而 039330a29 则不会.

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.

到目前为止，这是我所拥有的，但我不确定它是否正确

So far this is what I have but I am not sure that it is correct

[0-9]{1,45} 

我也试过

^[0-9]{45}*$

但这似乎也不起作用.我对正则表达式不是很熟悉，所以任何帮助都会很棒.谢谢！

but that does not seem to work either. I am not very familiar with regex so any help would be great. Thanks!

推荐答案

大功告成，您只需要开始锚点 (^) 和结束锚点 ($):

You are almost there, all you need is start anchor (^) and end anchor ($):

^[0-9]{1,45}$

\d 是字符类 [0-9] 的缩写.您可以将其用作:

\d is short for the character class [0-9]. You can use that as:

^\d{1,45}$

锚点强制模式匹配整个输入，而不仅仅是它的部分.

The anchors force the pattern to match entire input, not just a part of it.

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.

Your regex [0-9]{1,45} looks for 1 to 45 digits, so string like foo1 also get matched as it contains 1.

^[0-9]{1,45} 查找 1 到 45 位数字，但这些数字必须位于开头输入.它匹配 123 但也匹配 123foo

^[0-9]{1,45} looks for 1 to 45 digits but these digits must be at the beginning of the input. It matches 123 but also 123foo

[0-9]{1,45}$ 查找 1 到 45 位数字，但这些数字必须位于结尾输入.它匹配 123 但也匹配 foo123

[0-9]{1,45}$ looks for 1 to 45 digits but these digits must be at the end of the input. It matches 123 but also foo123

^[0-9]{1,45}$ 查找 1 到 45 个数字，但这些数字必须两者在开始和结束输入，实际上它应该是整个输入.

^[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.

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