Regular Expression to avoid negative values

Question

I am totally new to creating my own regular expressions. I have one reg ex developed my team member as listed below

  ^\s*-?\d{1,3}(\.\d{1,4})?\s*$

This will ensure that the value entered is having a maximum of 3 digits and may or may not have a negative sign.

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If I test with a value, “-1000” it will say the entered value does not meet the requirements and an error will be shown to the user.

I need to modify the expression in such way that:

If a “-“ sign is there, it can have more than 3 digits and decimals. [But if the user enter a “-“ and any alphabets, it should not match ]

Denys Séguret · Accepted Answer · 2013-10-10 14:56:28Z

1

You could change it to this one :

^\s*(\d{1,3}|-\d+)(\.\d{1,4})?\s*$

The first part in the form (a|b) means a or b. It means that the part before the comma is either

1 to 3 digits
or - followed by at least one digit

edited Oct 10, 2013 at 14:56

answered Oct 10, 2013 at 14:41

Denys Séguret

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2 Comments

LCJ Over a year ago

Thanks, Can you please explain why you modified the below one? ^\s*(\d{1,3}|-\d{1,})(\.\d{1,4})?\s*$

Denys Séguret Over a year ago

I just thought that \d+ was cleaner than \d{1,}. It's the same.

Anirudha · Accepted Answer · 2013-10-10 15:06:33Z

1

Use |(OR) operator in regex

^(\d{1,3}([.]\d{1,4})?|-\d+([.]\d+)?)$

edited Oct 10, 2013 at 15:06

answered Oct 10, 2013 at 14:47

Anirudha

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Comments

Bob Brinks · Accepted Answer · 2013-10-10 14:43:01Z

-1

If you just want to validate if a number is between -999 and 999 please parse it to an Integer and check -999 < x < 999.

answered Oct 10, 2013 at 14:43

Bob Brinks

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