C# regex for conditional operators example eq:2 , ne:3

Question

I wanted to write an regex in C# for strings which can comprise of any operator and operand value. These operators are string characters like eq for equals , ct = contains & bt for between , eq for equals.

i get strings into backend like eq=4. But during test someone tested my code with garbage values to my API and the string was eq:**+4.

Now i want to build an regex such that it will validate string against regex values like eq:5 or bt:8-9.

JUST A NOTE : exlcuding between operator no other operator should have such value like eq:4-6.

i have done this @"^\\b(eq | ne | gt | lt | ge | le | ct | bt)\\w\\b : ? (\\d | - ) ? \\d"

seems im close but need some guidance to get this properly working.

Any help or suggestion is welcome.

Answer 1

(eq|ne|gt|lt|ge|le|ct|bt):-?[0-9]+(--?[0-9]+)?

or with named group: @"(?<operator>eq|ne|gt|lt|ge|le|ct|bt):(?<firstValue>-?[0-9]+)(-(?<secondValue>-?[0-9]+))?$"

demo : https://regex101.com/r/HWnIq9/1

Answer 2

You can use

@"^(eq|[gln]e|[bclg]t)\s*:\s*\d+(?:\.\d+)?(?:-\d+(?:\.\d+)?)?\z"

See the regex demo . Details :

• ^ - start of string
• (eq|[gln]e|[bclg]t)
• \\s*:\\s* - a colon enclosed with zero or more whitespaces
• \\d+(?:\\.\\d+)? - an int/float number (one or more digits and then an optional sequence of a dot and one or more digits)
• (?:-\\d+(?:\\.\\d+)?)? - an optional sequence of a - , one or more digits and then an optional sequence of a dot and one or more digits
• \\z - the very end of string.

See the difference between $ and \\z anchors in .NET regex.