datagridview cell accepts only numbers and some special character

Question

My requirement is to allow only numbers,.,<,- and < in certain columns on my datagridview.The example inputs are 2.5,1-15.5,>10,>12.54,<75 etc

I'm using regex to check the pattern matching following is my code

If System.Text.RegularExpressions.Regex.IsMatch(val, "^[\d.-]+$") Then
            Return True
        Else
            Return False
        End If

But this accepts only numbers,. and - that means which return true if I pass val="2.5" or val="5-10"

So my question is how to make it for other symbols(>,<)

Answer 1

To make a structural check and be space relaxed you may use something like this:

^(\s*(?:[-><])?\s*\d+(?:[.]\d+)?)+$

Try the regex demo.

This accept also: 1.5 - 10.3 or < 10 but refuse invalid < 10.2. or 1 - .. accepted before.

Update To accept only single number disequality (accept < 10.2 but refuse >10 <5) and accept at max 2 operands in subtractions (accept 1.2 - 3.4 but refuse 1 -1 - 1) (as stated by @SebastianProske):

^(\s*[><]\s*\d+([.]\d+)?|\d+([.]\d+)?\s*(-?\s*\d+([.]\d+)?\s*)?)$

Regex Demo

PS: to be more precise we can replace all the \s with [ \t] to not accept newlines and other whitespace chars.