using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"\b(34[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b34[0-9]{13}\b|\b(37[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b37[0-9]{13}\b";
string input = @"American Express
Requirements: American Express cards start with the number 34 or 37 and have 15 digits. Pattern is 4-6-5 when having spaces or dashes.
Pattern Parts:
Starts with number 34 and 15 length:
1) \b(34[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b34[0-9]{13}\b
Starts with number 37 and 15 length:
2) \b(37[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b37[0-9]{13}\b
Combining 1-2 to form one pattern:
\b(34[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b34[0-9]{13}\b|\b(37[0-9]{2}[ -])([0-9]{6}[ -])[0-9]{5}\b|\b37[0-9]{13}\b
Test Cases:
Positive (Should fire):
15 length, no space, start with 34 342312341234112
15 length, dashes, start with 34 3423-123456-12345
15 length, spaces, start with 34 3423 123456 12345
15 length, no space, start with 37 372112341234123
15 length, dashes, start with 37 3721-123456-12345
15 length, spaces, start with 37 3721 123456 12345
Embedded in sentence with space:
15 length, no space, start with 34 Here is the cc: 342312341234112
15 length, dashes, start with 34 Here is the cc: 3423-123456-12345
15 length, spaces, start with 34 Here is the cc: 3423 123456 12345
15 length, no space, start with 37 Here is the cc: 372112341234123
15 length, dashes, start with 37 Here is the cc: 3721-123456-12345
15 length, spaces, start with 37 Here is the cc: 3721 123456 12345
15 length, no space, start with 34 Credit Card#:342312341234112
15 length, dashes, start with 34 Credit Card#:3423-123456-12345
15 length, spaces, start with 34 Credit Card#:3423 123456 12345
15 length, no space, start with 37 Credit Card#:372112341234123
15 length, dashes, start with 37 Credit Card#:3721-123456-12345
15 length, spaces, start with 37 Credit Card#:3721 123456 12345
Negative (Should Not Fire):
15 length, no space, not start with 34 352312341234112
15 length, dashes, not start with 34 3523-123456-12345
15 length, spaces, not start with 34 3523 123456 12345
15 length, no space, not start with 37 362112341234123
15 length, dashes, not start with 37 3621-123456-12345
15 length, spaces, not start with 37 3621 123456 12345
15 length, no space, start with 34, embedded Credit Card Number342312341234112
15 length, dashes, start with 34, malformed 3423-1234-1234-112
15 length num matching pattern but embedded User ID: 000000342312341234112000000";
RegexOptions options = RegexOptions.Multiline;
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