Common Mistakes and How to Avoid Them in C#

Introduction

In this article, we will cover Common mistakes and how to avoid them with C#.

So, Let's get started.

C# is a strongly typed language with many cool features to help us develop software with greates ease. We can however still make mistakes and many of them are quite common.

Here are common C# mistakes that are often made and how to avoid them!

Stop checking null with the if statement

The if statement can have an enormous number of utilities and uses. One of them is to use it to check null. Although this is the correct way, it can be stated a little better.

Avoid this

if(result != null)
{
  if(result.data != null) 
  {
    return result.data.appRun;    
  }			  
}

Try this

return result?.data?.appRun;

Use Tuples instead of classes

If you want to return more than one result, the first thing that will probably come to mind is to create a class just for that purpose. This is the correct way to do it but not the best way to do it.

Avoid this

public ResultInfo GetInfo() 
{
  var result = new ResultInfo 
  {
	Path = "C:/desktop/vyelve/Test",
	Name = "Result.exe";
  };
}

Try this

public (string path, string name) GetApplicationInfo() 
{
  return ("C:/desktop/vyelve/Test","Result.exe");
}

Usage of String Concatenation

Avoid this

var values = new List<string>() {"Hello ", "C# ", "Corner", "!"};
string outputValue = string.Empty;

foreach(var value in values) 
{
  outputValue += value;   // Creates a copy of the string in memory 
}
Console.WriteLine(outputValue);

Try this

var values = new List<string>() {"Hello ", "C# ", "Corner", "!"};
			
StringBuilder outputValueBuilder = new StringBuilder(); 
foreach(var value in values) 
{
  outputValueBuilder.Append(value);
}
Console.WriteLine(outputValueBuilder);

Incorrect Evaluation of the Default value for uninitialized variables

Avoid this

public class Program
{
  static Point point;
  static Pen pen; 

  public static void Main(string[] args)
  {
	 Console.WriteLine(pen == null); // True
	 Console.WriteLine(point == null);  // False 
  }
}

Try this

public class Program
{
  static Point point;
  static Pen pen; 

  public static void Main(string[] args)
  {
	 Console.WriteLine(pen.IsEmpty);
	 Console.WriteLine(point.IsEmpty);
  }
}

Don't use Throw ex

Avoid this

catch(SomeException ex) 
{
  logger.log(ex);
  throw ex;
}

Try this

catch(SomeException ex) 
{
  logger.log(ex);
  throw;
}

Using T Casting

Avoid this

var man = (Man)person;

Try this

var man = person as Man;