My regex for matching decimal numbers matches "1." How can I fix it?

I got this regular expression for decimals:

开发者_如何学运维/^(\d{1,3})(\.{0,1}\d{0,2})$/

But It allows "1."

How could I fix this?

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The following regex matches 1-3 digits, optionally followed by a decimal point and 1-2 digits.

/^(\d{1,3})(\.\d{1,2})?$/

Note that I also changed your . to \.. It is a metacharacter that matches anything, and so it has to be escaped.

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/^(\d{1,3})(\.\d{1,2})?$/

I assume you're trying to match between 0 and 999.99, with 0, 1, or 2 decimals. If there are no decimals, you want no period separator. If that's the case, you want to the above.

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For what it's worth, if you don't want to force a 0 at the beginning of the number, you can use the following expression:

(\d*\.)?\d+

This will match:

1
.1
1.1

This will not match:

1.
.

With some modification, this expression can still be used to force a certain number of digits:

(\d{1,3}\.)?\d{1,2}