how can I specify a regex that allows numbers from -20 to 20, including 0 and decimal points?

e.g all of the following are allowed:

20 19.99 5 0.5 0 1 3.45 -20 -17.20

CodePudding user response：

If you're looking for a regex for your task, you can use this one:

^-?1?\d(\.[\d] )?$|^-?20$

Explanation:

• ^: start of number
• -?: optional minus
• 1?: optional 1 for tens
• \d: any digit for units
• (\.[\d] )?: optional decimal places with any digit
• $: end of number

or

• ^: start of number
• -?: optional minus
• 20: 20
• $: end of number