How do I include negative decimal numbers in this regular expression?

regex numbers
user1786107 picture user1786107 · Apr 4, 2013 · Viewed 171.7k times · Source

How do I match negative numbers as well by this regular expression? This regex works fine with positive values, but I want it to also allow negative values e.g. -10, -125.5 etc. 

^[0-9]\d*(\.\d+)?$

Thanks

Answer

Mike Perrenoud picture Mike Perrenoud · Apr 4, 2013

You should add an optional hyphen at the beginning by adding -? (? is a quantifier meaning one or zero occurrences):

^-?[0-9]\d*(\.\d+)?$

I verified it in Rubular with these values:

10.00
-10.00

and both matched as expected.

Related questions

How to extract numbers from a string in Python?

I would extract all the numbers contained in a string. Which is the better suited for the purpose, regular expressions or the isdigit() method? Example: line = "hello 12 hi 89" Result: [12, 89]

Read More
Extract a number from a string (JavaScript)

I have a string in JavaScript like #box2 and I just want the 2 from it. I tried: var thestring = $(this).attr('href'); var thenum = thestring.replace( /(^.+)(\w\d+\w)(.+$)/i,'$2'); alert(thenum); It still returns #box2 in the …

Read More
Remove insignificant trailing zeros from a number?

Have I missed a standard API call that removes trailing insignificant zeros from a number? Ex. var x = 1.234000 // to become 1.234; var y = 1.234001; // stays 1.234001 Number.toFixed() and Number.toPrecision() are not quite what I'm looking for.

Read More