仅与这些情况匹配的正则表达式

Question

I have a regular expression in c# that should return IsMatch = true only when the input has the desired pattern but actually is returning true if some of the characters matches...How would be the correct regular expression?

Regex reg = new Regex(@"[0-9 \-+]"); //accept only numbers, spaces, minus character and plus character

string formularight="1123 - 4432+32124";//its correct

bool validformat=reg.IsMatch(formularight)) //returns true, ok

string formulawrong="1123a - 4432+32124"; //it has one letter ismatch should be false...

validformat=reg.IsMatch(formulawrong)) //returns true, not ok

I check later if each number is followed by a minus or plus sign before the next number but if it can be included in the regex validation...

I checked other regex questions and before someone suggest that i use a datatable to compute() the expresion or use some calculator logic please know that in this case the numbers are used like fields names that i will use to get some values from the database not numerical values per se. So i only need the regex validation before parsing the formula. Thanks

Valid examples for regex:
11123
112 - 1121
112-1121
1221111+554-111135678
44332-54-114

Invalid examples (letters present, not a + or - between numbers,...):
112 -
6543e
112 1121
6543e + 4432
-7632

Answer 1

Your Regular Expression finds several matches, because you didn't force it to match the whole input.

By using the following anchors, it will be forced to check the entire input.

• ^ - Start
• $ - End

Regex:

^[0-9 \-+]*$

Regexr: http://regexr.com/3b97l

Answer 2

You should start and end anchors in your regex:

Regex reg = new Regex(@"^[0-9 +-]+$");

to make sure whole input matches given set of characters.

isMatch Reference

Answer 3

How about:

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

This works for your valid and invalid examples.

In order to match numbers in brackets:

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