正则表达式首先避免超过一个零

Question

i want to regex that match the following case: it will be used for input field as pattern;

case:

1. 000   //not match
2. 100.000  //match
3. 0         //match
4. 0.0    //match
5. 0.01   //match
6. 00100   // not match    
7. 001.1   //not match
8. 101   // match 
9. 0.0.01 //not match
10. 02001 // not match

i try with [0-9]+(\.[0-9][0-9]?)?

i will use in the input field as pattern. please help me.

<input type="text"  required="" pattern="[0-9]+(\.[0-9][0-9]?)?"  name="bstatus[bstatus_amount][]">

</div>

Answer 1

You can negate with a lookahead that asserts the absence of zero leading digits, and duplicate dots:

^(?!0\d|[^.]*\.[^.]*\.)\d+(\.\d\d?)?

Here is a regex demo.

Though considering your use case, what you need is simply:

^(?!0\d|[^.]*\.[^.]*\.)\d

Here is a regex demo.

echo preg_match('/^(?!0\d|[^.]*\.[^.]*\.)\d/', $str);