Question

One last Regex problem I need help with. What I am trying to do is be able to parse a math expression, while still having my Regex recognize unary symbols. I am using the following to parse an integer:

[\+\-]?[0-9]+

Which works fine in these 2 scenarios:

myVar = -5
myVar = +5

Regex correctly identifies both -5 and +5 as integers. My problem is if I have a scenario like this:

myVar = 7-5

This, however, gets matched correctly:

myVar = 7*-5

Now what Regex is doing in the 7-5 scenario is its identifying 2 integers, 7 and -5. In reality, what I want is for it to be able to identify an integer (7), a minus sign (-) and then another integer (5). What Regex pattern do I need to do this?

Thanks in advance. This is .NET Regex, by the way.

Answer 1

Regex isn’t the best choice for parsing math expressions. Look at Recursive descent parser or Reverse Polish notation or other more appropriate algorithm.