Validate mathematical expressions using regular expression?

Question

I want to validate mathematical expressions using regular expression. The mathematical expression can be this

1. It can be blank means nothing is entered

Answer 1

Something like this should work:

^([-+/*]\d+(\.\d+)?)*

Regexr Demo

• ^ - beginning of the string
• [-+/*] - one of these operators
• \d+ - one or more numbers
• (\.\d+)? - an optional dot followed by one or more numbers
• ()* - the whole expression repeated zero or more times