Unique RegEx string

Question

I have a set of requirements which state that the input must be validated as follows:

• Be between 1 and 7 characters
• Numeric
• Greater than 0
• and allow a decimal point

Currently I have ^(?!0{1,7}$)(\d+(\.\d)?){1,7}$

But this does not limit the overall string to a maximum of 7 characters

Answer 1

We can think this way:

^(?=\d+(?:\.\d+)?$)(?![0\.]+$).{1,7}$

• Positive lookahead from the beginning: it should be composed of digits and optional . symbol (number pattern)
• Negative lookahead from the beginning: it shouldn't be composed only of 0 and . symbols (pattern to exclude 0 value).
• It should have between 1 and 7 symbols.