using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(0\.5)|(\.5)|([0-9]*?)\.5((?(1)| ))";
string substitution = @"\{3}\{4}1/2\{4}";
string input = @"skdsd .5 cups";
Regex regex = new Regex(pattern);
string result = regex.Replace(input, substitution, 1);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx