Matching math expression with regular expression?

Posted by Ethan on Stack Overflow See other posts from Stack Overflow or by Ethan
Published on 2010-04-07T19:23:10Z Indexed on 2010/04/07 19:43 UTC
Read the original article Hit count: 512

Filed under:

regex

For example, these are valid math expressions:

a * b + c
-a * (b / 1.50)
(apple + (-0.5)) * (boy - 1)

And these are invalid math expressions:

--a *+ b @ 1.5.0  // two consecutive signs, two consecutive operators, invalid operator, invalid number
-a * b + 1)  // unmatched parentheses
a) * (b + c) / (d  // unmatched parentheses

I have no problem with matching float numbers, but have difficulty with parentheses matching. Any idea? If there is better solution than regular expression, I'll accept as well. But regex is preferred.

Related posts about regex

Find multiple regex in each line and skip result if one of the regex doesn't match

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a list of variables: variables = ['VariableA', 'VariableB','VariableC'] which I'm going to search for, line by line ifile = open("temp.txt",'r') d = {} match = zeros(len(variables)) for line in ifile: emptyCells=0 for i in range(len(variables)): regex = r'('+variables[i]+r')[:|=|\(](-… >>> More
OWASP Regex Repository: Is this regex correct?

as seen on Stack Overflow - Search for 'Stack Overflow'
I was looking at the regular expression for validating various data types from the (OWASP Regex Repository). One of the regular expressions in there is called safetext and looks like: ^[a-zA-Z0-9\s.\-]+$ My first question is: Is this regular expression correct? complementary question If this… >>> More
Make a Perl-style regex interpreter behave like a basic or extended regex interpreter

as seen on Stack Overflow - Search for 'Stack Overflow'
I am writing a tool to help students learn regular expressions. I will probably be writing it in Java. The idea is this: the student types in a regular expression and the tool shows which parts of a text will get matched by the regex. Simple enough. But I want to support several different regex… >>> More
JS regex isn't matching, even thought it works with a regex tester

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm writing a piece of client-side javascript code that takes a function and finds the derivative of it, however, the regex that's supposed to match with the power rule fails to work in the context of the javascript program, even though it sucessfully matches when it's used with an independent regex… >>> More
c# RegEx with "|"

as seen on Stack Overflow - Search for 'Stack Overflow'
I need to be able to check for a pattern with | in them. For example an expression like d*|*t should return true for a string like "dtest|test". I'm no regex hero so I just tried a couple of things, like: Regex Pattern = new Regex("s*\|*d"); //unable to build because of single backslash Regex Pattern… >>> More

Developer IT

Matching math expression with regular expression? - Developer IT

Matching math expression with regular expression?

regex

Related posts about regex

Find multiple regex in each line and skip result if one of the regex doesn't match

OWASP Regex Repository: Is this regex correct?

Make a Perl-style regex interpreter behave like a basic or extended regex interpreter

JS regex isn't matching, even thought it works with a regex tester

c# RegEx with "|"

Categories cloud