[Solved] C# Error: Class does not contain a constructor that takes arguments

This is a build error in C#. This error “ClassName does not contain a constructor that takes N arguments” is thrown when you do not write a constructor that accepts those number of arguments you sent while creating the object.

Example

Let us recreate a scenario in which we do not define any constructor but tried to create an object with values passed as arguments.

Program.cs

using System;

namespace CSharpExamples {
    class Book{
        public string author;
        public string title;

        public void printBookDetails(){
            Console.WriteLine("\n---Book Details---\n==================");
            Console.WriteLine("Title  : "+title);
            Console.WriteLine("Author : "+author);
        }
    }
    class Program {
        static void Main(string[] args) {
            Book book1 = new Book("C# Tutorial", "TutorialKart");
            book1.printBookDetails();
        }
    }
}

Output

Program.cs(16,30): error CS1729: 'Book' does not contain a constructor that takes 2 arguments [D:\workspace\csharp\HelloWorld\HelloWorld.csproj]
Program.cs(6,23): warning CS0649: Field 'Book.title' is never assigned to, and will always have its default value null [D:\workspace\csharp\HelloWorld\HelloWorld.csproj]
Program.cs(5,23): warning CS0649: Field 'Book.author' is never assigned to, and will always have its default value null [D:\workspace\csharp\HelloWorld\HelloWorld.csproj]

The build failed. Please fix the build errors and run again.

Solution

For this to work out we need to either add a constructor to class Book that takes 2 arguments or create book1 object with no arguments.

using System;

namespace CSharpExamples {
    class Book{
        public string author;
        public string title;

        public Book(string Title, string Author){
            title = Title;
            author = Author;
        }
        
        public void printBookDetails(){
            Console.WriteLine("\n---Book Details---\n==================");
            Console.WriteLine("Title  : "+title);
            Console.WriteLine("Author : "+author);
        }
    }
    class Program {
        static void Main(string[] args) {
            Book book1 = new Book("C# Tutorial", "TutorialKart");
            book1.printBookDetails();
        }
    }
}

Output

---Book Details---
==================
Title  : C# Tutorial
Author : TutorialKart

Conclusion

In this C# Tutorial, we learned how to fix C# Error: “Class does not contain a constructor that takes arguments”.