Practicing and exploring

Test your knowledge and understanding by answering some questions, get some hands-on practice, and explore with deeper research into topics of this chapter.

Exercise 4.1 – test your knowledge

Use the Web to answer the following questions:

1. Does every assembly you create have a reference to the mscorlib.dll assembly?
2. What is the maximum number of characters that can be stored in a string?
3. When and why should you use a SecureString?
4. When should you use a LinkedList?
5. When should you use a SortedDictionary class rather than a SortedList class?
6. Why should you not use the official standard for e-mail addresses to create a regular expression for validating a user's e-mail address?

Exercise 4.2 – practice regular expressions

Create a console application named Ch04_Exercise02 that prompts the user to enter a regular expression, and then prompts the user to enter some input and compare the two for a match until the user presses Esc:

The default regular expression checks for at least one digit.
Enter a regular expression (or press ENTER to use the default): ^[a-z]+$
Enter some input: apples
apples matches ^[a-z]+$? True
Press ESC to end or any key to try again.
Enter a regular expression (or press ENTER to use the default): ^[a-z]+$
Enter some input: abc123xyz
abc123xyz matches ^[a-z]+$? False
Press ESC to end or any key to try again.

Exercise 4.3 – explore topics

Use the following links to read in more detail the topics covered in this chapter:

• .NET Blog: A first hand look from the .NET engineering team: http://blogs.msdn.com/b/dotnet/
• Assemblies and the Global Assembly Cache (C# and Visual Basic): https://msdn.microsoft.com/en-us/library/ms173099.aspx
• String Class: https://msdn.microsoft.com/en-us/library/system.string(v=vs.110).aspx
• StringBuilder Class: https://msdn.microsoft.com/en-us/library/system.text.stringbuilder(v=vs.110).aspx
• Regex Class: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx
• How to: Search Strings Using Regular Expressions (C# Programming Guide): https://msdn.microsoft.com/en-us/library/ms228595.aspx
• Regular Expression Language - Quick Reference: https://msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx
• RegExr: Learn, Build, & Test RegExr: http://regexr.com/
• Collections (C# and Visual Basic): https://msdn.microsoft.com/en-us/library/ybcx56wz.aspx
• List<T> Class: https://msdn.microsoft.com/en-us/library/6sh2ey19(v=vs.110).aspx
• Dictionary<TKey, TValue> Class: https://msdn.microsoft.com/en-us/library/xfhwa508(v=vs.110).aspx
• Stack<T> Class: https://msdn.microsoft.com/en-us/library/3278tedw(v=vs.110).aspx
• Queue<T> Class: https://msdn.microsoft.com/en-us/library/7977ey2c(v=vs.110).aspx
• SortedList<TKey, TValue> Class: https://msdn.microsoft.com/en-us/library/ms132319(v=vs.110).aspx
• SortedDictionary<TKey, TValue> Class: https://msdn.microsoft.com/en-us/library/f7fta44c(v=vs.110).aspx