Stings are a difficult and sometimes touchy subject when it comes to programming. In the C language improper use of strings can crash your whole system. Even some professors in Colleges and Universities do not teach their students how the native string functions in the C language work simply because they consider them far too dangerous for students to learn.
I will try to cover the best practices of handling strings that I have picked up over the years in the hope that it will either improve your performance or stop you from making some of the blunders I have made in the past.
Best Practice #1
Pertains to Visual Basic
It is always best to use the & to concatenate strings instead of the + operator.
The reasoning:
The + operator was only kept for historical reasons. It is far better to use the & operator because it make your code easier for other programmers to read it.
Best Practice #2
Use a char variable instead of a string variable only if you are certain you need to store only one character.
The reasoning:
The char variable takes up less space than a 1 character string.
Best Practice #3
Always explicitly initialize string variables to a zero length string.
The reasoning:
By explicitly initializing a string variable you avoid NullReferenceException errors when you reference the string.
Best Practice #4
You should always return an empty string when defining a method or property when the end result string has no characters.
The reasoning:
This simplifies the task of the calling code which will then not have to test for a null.
Best Practice #5
Never use language specific string functions.
The reasoning:
Language specific functions always perform worse their .Net native methods.
Best Practice #6
When checking for empty strings compare the length property with zero rather than with a String.Empty
The reasoning:
Checking the string length for zero has better performance then with the String.Empty method.
Best Practice #7
When comparing two strings use the String.Compare method to compare strings in case insensitive mode.
The reasoning:
The ToUpper and ToLower methods both create a new string and by doing this affect the memory heap. Also the Compare static method is far faster then using the ToUpper and ToLower string functions because there is no need to create new strings and then compare them.
Best Practice #8
Always use the Regex type to validate string input by the user or read from an external source such as the file system.
The Reasoning:
You should always validate input from any source that could affect the security or performance of your application.
Best Practice #9
Never hard code any value or variable that may change once the application goes into production. Instead store those values in a config file that your program can use to update those values dynamically.
The reasoning:
You simply do not want to have to update the entire program simply because something has changed in the production environment. This is a headache you simply want to avoid at all costs.
Best Practice #10
Avoid hard coded strings that may appear in the user interface. Instead use a resource file instead.
The reasoning:
You always want to avoid any programming that would make it difficult in the future to update your application.