I have this pattern:
我有这种模式：
[0-9]*\.?[0-9]
It matches numbers but it also matches 3.5.4 as:
它匹配数字但它也匹配3.5.4：
- 3.5
- 3.5
- .4
- 0.4
How to fix that(this input shouldn't be matched)?
UPDATE:
this also should work on input: 1 3.5.4 10
如何解决（这个输入不应该匹配）？更新：这也应该适用于输入：1 3.5.4 10
1.2. is not allowed
.3 is allowed
1.2。是不允许的.3是允许的
any char that is not poart of numer is not allowed, like: a1 2.4f 3. 45, 67!
任何不是numer的字符都是不允许的，例如：a1 2.4f 3. 45,67！
5 个解决方案
#1
10
Updated answer after comment from poster:
海报评论后更新的答案：
Use lookahead / lookbehind to make sure that the characters before and after are spaces:
使用lookahead / lookbehind确保前后的字符是空格：
Here's a version that closely matches yours, but that won't make partial matches:
这是一个与您的版本非常匹配的版本，但不会进行部分匹配：
(?:^|(?<=\s))[0-9]*\.?[0-9](?=\s|$)
For both these examples, when run on the string 1 2.3.4 5.6 it matches only 1 and 5.6.
对于这两个示例，当在字符串1 2.3.4 5.6上运行时，它仅匹配1和5.6。
#2
12
To match a json number:
要匹配json数字：
^[-]?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?$
Use this regex to match .123:
使用此正则表达式匹配.123：
^[-]?((0|[1-9][0-9]*)(\.[0-9]+)?|\.[0-9]+)([eE][+-]?[0-9]+)?$
#3
7
You have to decide if you want to accept numbers without leading zeros (eg .123). If you don't then the regex is easy:
您必须决定是否要接受不带前导零的数字（例如.123）。如果你不这样，那么正则表达式很简单：
^-?[0-9]+(\.[0-9]+)?$
If you do then it's a little more complex:
如果你这样做，它会更复杂一些：
^-?(?:[0-9]+|[0-9]*\.[0-9]+)$
Both presume that a decimal point must be followed by at least one digit. If you don't accept negative numbers then the leading -? is unnecessary.
两者都假设小数点后面必须至少跟一个数字。如果你不接受负数那么领先 - ？是不必要的。
#4
2
Your regex is not anchored. If you want to match lines that contain only numbers and nothing else use:
你的正则表达式没有锚定。如果要匹配仅包含数字的行，则不使用其他内容：
^[0-9]*\.?[0-9]$
#5
1
You should not use a regex for this unless you really need to.
除非你真的需要，否则你不应该使用正则表达式。
Instead, you should use your language's built-in number parsing methods.
相反，您应该使用您的语言的内置数字解析方法。
I assume from your other questions that you're using Javascript; if so, you should call parseFloat.
我从你的其他问题中假设你正在使用Javascript;如果是这样，你应该调用parseFloat。
#1
10
Updated answer after comment from poster:
海报评论后更新的答案：
Use lookahead / lookbehind to make sure that the characters before and after are spaces:
使用lookahead / lookbehind确保前后的字符是空格：
Here's a version that closely matches yours, but that won't make partial matches:
这是一个与您的版本非常匹配的版本，但不会进行部分匹配：
(?:^|(?<=\s))[0-9]*\.?[0-9](?=\s|$)
For both these examples, when run on the string 1 2.3.4 5.6 it matches only 1 and 5.6.
对于这两个示例，当在字符串1 2.3.4 5.6上运行时，它仅匹配1和5.6。
#2
12
To match a json number:
要匹配json数字：
^[-]?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?$
Use this regex to match .123:
使用此正则表达式匹配.123：
^[-]?((0|[1-9][0-9]*)(\.[0-9]+)?|\.[0-9]+)([eE][+-]?[0-9]+)?$
#3
7
You have to decide if you want to accept numbers without leading zeros (eg .123). If you don't then the regex is easy:
您必须决定是否要接受不带前导零的数字（例如.123）。如果你不这样，那么正则表达式很简单：
^-?[0-9]+(\.[0-9]+)?$
If you do then it's a little more complex:
如果你这样做，它会更复杂一些：
^-?(?:[0-9]+|[0-9]*\.[0-9]+)$
Both presume that a decimal point must be followed by at least one digit. If you don't accept negative numbers then the leading -? is unnecessary.
两者都假设小数点后面必须至少跟一个数字。如果你不接受负数那么领先 - ？是不必要的。
#4
2
Your regex is not anchored. If you want to match lines that contain only numbers and nothing else use:
你的正则表达式没有锚定。如果要匹配仅包含数字的行，则不使用其他内容：
^[0-9]*\.?[0-9]$
#5
1
You should not use a regex for this unless you really need to.
除非你真的需要，否则你不应该使用正则表达式。
Instead, you should use your language's built-in number parsing methods.
相反，您应该使用您的语言的内置数字解析方法。
I assume from your other questions that you're using Javascript; if so, you should call parseFloat.
我从你的其他问题中假设你正在使用Javascript;如果是这样，你应该调用parseFloat。