Question

I am trying to add a bracket to operands of OR operator. For example, if I have statement as below,

C>O AND C>4 OR C>0 AND C>5

I would like to format it as below

(C>O AND C>4) OR (C>0 AND C>5)

I wrote a simple code to do this as below. However, if the string has more than one OR statements the code doesn’t work properly. I was told that the regular expression could accomplish this. But I have very minimum knowledge in regular expression.

string mystring = "C>O AND C>4 OR C>0 AND C>5";
int indexFound = mystring.IndexOf("OR");
string left = mystring.Substring(0, indexFound - 1);
string right = mystring.Substring(indexFound + 2, mystring.Length - (indexFound + 2));
string output = "(" + left + ")" + "OR" + "(" + right + ")";

Any help would be appreciated.

Answer 1

Here is the way via regular expressions:

static string AddBracketsToOr(string input)
{            
    Regex regex = new Regex(@"(?<left>.+[AND|OR].+) OR (?<right>.+[AND|OR].+)");
    Match match = regex.Match(input);

    if (match == null)
        throw new Exception("Wrong input format");

    return String.Format("({0}) OR ({1})", 
                         match.Groups["left"], match.Groups["right"]);
}

Usage:

var result = AddBracketsToOr("C>O AND C>4 OR C>0 AND C>5");

UPDATE:
Works with

"C>O AND C>4 OR C>0 AND C>5" // (C>O AND C>4) OR (C>0 AND C>5)
"C>9 OR C>O AND C>4 OR C>0 AND C>5" // (C>9 OR C>O AND C>4) OR (C>0 AND C>5)
"C>9 OR C>O OR C>0 AND C>5" // (C>9 OR C>O) OR (C>0 AND C>5)