C# Question
Regex expression to divide mathematical and logical expression C#
I'm trying to find a way of dividing an expression into parts with regex. I'm currently splitting everything by spaces but that's not the correct way of doing it. Here is an example expression:
var expression = "#X+ 23>=#Threshold && #X * 4 != 54 || #IgnoreCheck"
The result I'm looking for is a list of all the parts:
["#X", "+", "23", ">=", "#Threshold", "&&", "#X", "*", "4", "!=", "54", "||", "IgnoreCheck"]
The characters to take into account for spliting:
&& || != + = - * / ^ > < <= >=
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Answer Source
You may use
var res = Regex.Split(expression, @"\s*(&&|\|\||<=|>=|!=|[-+=*/^><])\s*");
See the regex demo. The main idea is to use alternation (|) since some alternatives are multicharacter strings.
Details
\s*- 0+ whitespace(&&|\|\||<=|>=|!=|[-+=*/^><])- capturing group 1 (thus, when used withRegex.Split, these parts will be output into the resulting array) matching&&- two ampersands|- or\|\|- 2 pipes|- or<=- a<and then=|- or>=- a>and then=|- or!=-!followed with=|- or[-+=*/^><]- any 1 symbol from this set
\s*- 0+ whitespace
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