using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?mi)(\d+)\.\h+(.+)(?:\R[a-e]\.\h+(.+))?(?:\R[a-e]\.\h+(.+))?(?:\R[a-e]\.\h+(.+))?(?:\R[a-e]\.\h+(.+))?(?:\R[a-e]\.\h+(.+))?\RAns:\h+(.+)";
string input = @"1. Question with 4 choices
a. one a
b. one b
c. one c
d. one d
Ans: B
23. True-False Question with no choices
Ans: T
2. Question with 3 choices
a. two a
b. two b
c. two c
Ans: C
3. Question with 2 choices
a. three a
b. three b
Ans: B";
RegexOptions options = RegexOptions.CultureInvariant;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
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