C# - Difference Between ToString() and Convert.ToString() Method

In this Tutorial, we am going to discuss the difference between Convert.ToString and ToString Method in C# with Examples. In C#, both ToString() and Convert.ToString() are used to convert a value to a string representation.

1. ToString() in C#

It is defined on every object in C#. It is used to convert the current instance of an object to its string representation.

Points to Remember

1. If the value being converted to a string is null, ToString() will throw a NullReferenceException
2. ToString() is a virtual method, which means that it can be overridden by derived classes to provide a custom implementation.
3. ToString() can only be called on an object instance. In C#, an object instance is a specific occurrence of a class or a struct that has been created in memory at runtime.

Point 1 - If the value being converted to a string is null, ToString() will throw a NullReferenceException.

Here is an example.

using System;
using System.Text;

namespace FirstProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Employee objemp = null;
            objemp.ToString();  // Will show error NullReferenceException
        }
    }
    public class Employee
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
}

Now run the above code will show a NullReferenceException error.

Point 2 - ToString() is a virtual method, which means that it can be overridden by derived classes to provide a custom implementation.

The following code creates a objemp object and calls its ToString() method. Here is an example.

using System;
using System.Text;

namespace FirstProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Employee objemp = new Employee { FirstName = "Rohatash", LastName = "25" };
            string personString = objemp.ToString();
            Console.WriteLine(personString); // Output: Name: Rohatash, Age: 25
        }
    }
    public class Employee
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public override string ToString()
        {
            return $"FirstName: {FirstName}, LastName: {LastName}";
        }
    }
}

Now run the above code.

Point 3 - ToString() can only be called on an object instance. In C#, an object instance is a specific occurrence of a class or a struct that has been created in memory at runtime.

using System;
using System.Text;

namespace FirstProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Employee objemp = new Employee();   // This creates a new instance of the Employee class in memory,                 
        }
    }
    public class Employee
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }       
    }
}

In the above code that line creates a new instance of the Employee class in memory. ToString() can be called on that object instance.

Employee objemp = new Employee(); // This creates a new instance of the Employee class in memory, 

2. Convert.ToString() in C#

It is defined in the System.Convert class. It is used to convert a value to its string representation.

Points to Remember

1. If the value being converted to a string is null, Convert.ToString() will return an empty string.
2. It is a static method and cannot be overridden.
3. It can be called on a value type directly.

Point 1 - If the value being converted to a string is null, Convert.ToString() will return an empty string.

using System;
using System.Text;

namespace FirstProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Employee objemp = null;           
            Console.WriteLine("Value of Object :" + Convert.ToString(objemp));
        }
    }
    public class Employee
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
}

Now run the above code will return an empty string.

Point 2 - It is a static method, which means that it can not be overridden.

The following code creates a objemp object and calls its ToString() method. Here is an example.

int x = 567;
string xString = Convert.ToString(x); // This is valid
Convert converter = new Convert();
string xString = converter.ToString(x); // This is invalid and will result in a compile-time error

In the above example we cannot create an instance of the `Convert` class and call ToString() on that instance, as shown in the second line of the code. This will result in a compile-time error, because ToString() is a static method that can only be called on the Convert class itself, not on an instance of the class.

Point 3 - It can be called on a value type directly.

The following code called Convert.ToString() method on a value type directly. Here is an example.

using System;
using System.Text;

namespace FirstProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            int x = 567;
            string mystring = Convert.ToString(x); // This will return "567"
            Console.WriteLine(mystring);
        }
    }        
}

Now run the above code will return 567.

Difference between ToString() and Convert.ToString() Method in C#