I am trying to match floating-point decimal numbers with a regular expression. There may or may not be a number before the decimal, and the decimal may or may not be present, and if it is present it may or may not have digits after it. (For this application, a leading +/- or a trailing ‘E123’ is not allowed). I have written this regex:
/^([\d]*)(\.([\d]*))?$/ Which correctly matches the following:
1 1. 1.23 .23 However, this also matches empty string or a string of just a decimal point, which I do not want.
Currently I am checking after running the regex that $1 or $3 has length greater than 0. If not, it is not valid. Is there a way I can do this directly in the regex?
I think this will do what you want. It either starts with a digit, in which case the decimal point and digits after it are optional, or it starts with a decimal point, in which case at least one digit is mandatory after it.