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.NET Coding Best Practices

, 20 Jan 2010
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.NET Coding Best Practices - Vinayak's thumb rulesDo not hard code strings/ numerics. Instead of that use constants as shown below.Bad practice int Count; Count = 100; if( Count == 0 ) { // DO something… }Good practice int Count; Count = 100; private...
.NET Coding Best Practices - Vinayak's thumb rules
     
  1. Do not hard code strings/ numerics. Instead of that use constants as shown below.
     
    Bad practice
     
     int Count;
     Count = 100;
     if(  Count  ==  0 )
     {
      // DO something…
     }
    
     
    Good practice
     
     int Count;
     Count = 100;
     private static const int ZERO  =  0;
     if(  Count  ==  ZERO )
      {
        // DO something…
      }
    
     
  2. For string comparison - Use String. Empty instead of “”
     
  3. By default keep the scope of member variables to ‘private’, based on the needs expand the scope either to protected or public or internal.
     

    1. Other advantage of making the scope private by default is that during XMLSerilaization, by default it will serialize all the public members.
     
  4. When we have to manipulate the strings inside a loop, use StringBuilder instead of string as shown below.
     
    Bad practice
     
     String  temp = String.Empty;
     for( int I = 0 ; I<= 100; i++)
     {
       Temp += i.ToString();
     }
    
     
    Good practice
     
      StringBuilder sb = new StringBuilder();
      for ( int I = 0 ; I<= 100; i++)
       {
         sb.Append(i.ToString());
        }
    
     
  5. Prefer Arrays over Collections for simple operations.
     
  6. Prefer Generic Collections over ArrayList
     
  7. Prefer Generic Dictionaries over HashTable *.
     
  8. Prefer StringCollections and StringDictionaries for String manipulations and storage.
     
  9. Use the appropriate data types.
     
    For ex: if you want to check for any status, prefer bool rather than int.
     
    Bad practice
     
      int Check = 0;
      if(Check == 0)
       {
         // DO something
        }
    
     
    Good practice
     
      bool Check = false;
      if(!Check)
        {
          // DO something
        }
    
     
  10. Use ‘as’ operator for type casting and before using that resultant value check for null.
     
    class A
     {
     }
     
    class B : A
     {
     }
     
    B objB = new B();
    A objA1  = (A) objB;
    A objA 2 = objB as A;
     
    if( objA2 != null)
    {
     //Do something
    }
    
     
  11. For WCF proxy creation, use the using statement
     
     using(Cerate the proxy)
      {
        //Do the required operation
       }
    
     
  12. Follow ‘Acquire late, release early’ rule for expensive resources such as Connection, File etc.
     
    For ex : if you want to make use of SqlConnection Object for any data operations, create the instance at the method level rather than at the class level.
     
     class MyData
      {
          public MyData()
            {
            }
          public List<Customer> GetAllCustomer()
            {
            using(SqlConnection objConnection = new SqlConnection(“Connection string”))
              {
    	        //Do the operation and get the required data..
              }
            }   
     }
    
     
    If you want to create the SqlConnection instance at the class level, ensure that you are implementing the IDisposable for the class and doing the cleanup of SqlConnection instance at the Dispose();
     
     class MyData : IDisposable
      {
         SqlConnection objConnection = default(SqlCOnnection);
         public MyData(){
           objConnection = new SqlCOnnection(“Connection string”);
         }
         public List<Customer> GetAllCustomer(){
           // By using objConnection get the required data
         }
         public void Dispose(){
          // Do the cleanup of SqlCOnnection
          if( objConnection != null ){
             if( objConnection.State == ConnectionState.Open){
     	    objConnection.Close();
             }
          }
        }
     }
    
     
  13. If you do not want anybody to extend your class functionalities, make it ‘sealed’ to get the inlining and compile time benefits
     
  14. Avoid declaring the ‘destructor’ for every class. This will increase the life time of the class which un necessarily makes them long lived
     
  15. Prefer using Thread Pool over manual threading.
     
  16. Do not make any calls to a method from the loop.
     
    For ex :
     
    Bad practice
     
    for( int i = 0; i<= 100; i++)
    {
    	Calculate(i);
    }
    
     
    Good practice
     
    for( int i = 0; i<= 100; i++)
    {
      //Inline the body of Calculate.
    }
    
     
  17. Do not handle exceptions inside a loop, rather handle looping logic inside try/catch
     
    For ex:
     
    Bad practice
     
    for(int i = 0 ; i<= 100; i++){
       try{
       }
       catch(Exception ex){
          throw ex;
       }
    }
    
     
    Good practice
     
      try{
        for(int i = 0 ; i<= 100; i++){
        }
      }
      catch(Exception ex){
       throw ex;
      }
    
     
  18. Do not handle application logic by using Exception.
     
    For ex :
     
    Bad practice
     
     try{
       int  x,y,z;
       x = 0;
       y = 10;
       z = y/x;
      }
     catch(DevideByZeroException ex){
       throw ex;
     }
    
     
    Good practice
     
      private static const int ZERO  =  0; 
      try{
        int x,y,z;
        x = 0;
        y = 10;
        if( x != ZERO){
          z = y/x;
        }
       }
      catch(Exception ex){
       }
    
     
  19. Prefer for/while loop over foreach
     
  20. For communication between the layers, prefer Data Transfer objects over DataSet/DataTables.
I hope this will help you all to improve the code quality!!
 
Happy programming
 
Regards,
-Vinayak

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Vinayaka Krishna Shenoy
Architect MindTree Ltd
India India
Motivated achiever who guides organizations in applying technology to business settings, provides added value, and creates project deliverables in a timely manner. An experienced Technical Consultant, have successfully led large project teams of more than 20 people from requirements gathering to implementation and support using C#, .NET ,ADO.NET, ADO.NET Entity Framework,ASP.NET,ASP.NET MVC, WCF and SQL Server.

Comments and Discussions

 
GeneralMy vote of 3 PinmemberChamila Ranasinghe15-Nov-12 17:39 
GeneralSome good ideas... PinmemberS. Töpfer25-Jan-10 22:05 
General[My vote of 2] Comment on the article Pinmemberjstemper21-Jan-10 6:27 
General#1, #2, #9, #15, #17, #18, #19 Pinmembersupercat920-Jan-10 6:05 
GeneralIf these are considered best practices... Pinmemberbhogan22-Dec-09 7:14 
GeneralMost are good tips... PinmemberSilic0re0922-Dec-09 3:44 
GeneralRe: Most are good tips... Pinmemberkornman0012-Jan-10 5:20 
For #17, you can avoid it by using a simple function for processing logic (which is where you would then place the try/catch). Half the time a function with try/catch-mes will have been called from a loop somewhere up the call stack. Personally I rarely try to create functions with large bodies statements but there are exceptional-cases which cause me to ignore this guidance.
 
I don't see too many cases where a small operation (where off loading one or two statements to a simple function would kind of be silly) would throw, unless it's just a function call itself.
 
It should also be mentioned that the CLR can inline functions with small code bodies. All the more reason we don't want to pre-optimize! We're not dealing with a native compiler (nor a framework without a type system) here so we shouldn't be so quick to think of tips which worked in some performance cases with them, in our mananged .NET.
 
Of course if you live and die by the #15 sword, then yes it will be unavoidable Poke tongue | ;-P

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