A Complete Guide - Difference Between Convert ToString and ToString in C#

Last Updated: 03 Jul, 2025

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Difference Between Convert.ToString and ToString in C# Explained in Detail

1. Method Source

ToString(): This is a method that is part of the System.Object class in .NET. Every class in C# implicitly inherits from System.Object and thus has access to the ToString method. When overridden in a class, ToString() is intended to provide a string representation of the object.
Convert.ToString(): This method is part of the System.Convert class and is used for converting a variety of data types to a string. It provides a more centralized and versatile approach for type conversion.

2. Null Handling

ToString(): When called on a null reference, it will throw a NullReferenceException. This is because ToString is a method that needs to be called on an instance of an object.
Convert.ToString(): When passed a null value, it will return an empty string (""). This behavior makes Convert.ToString safer to use when dealing with potentially null values.

3. Usage Patterns

ToString(): Typically used when you have a strongly typed object and you want a string representation of it. It’s often overridden in custom classes to provide meaningful output.
Convert.ToString(): Used when dealing with different data types or when you are not sure of the type of the data being converted. It’s particularly useful in scenarios like data binding, where the type of data could vary.

4. Performance

ToString(): Generally faster than Convert.ToString() because it is a method specifically designed for the object in question, avoiding the overhead of general conversion logic.
Convert.ToString(): Since it involves more complex logic to handle different types, it can be slightly slower compared to ToString(). However, the performance difference is usually negligible unless in very high-frequency conversion scenarios.

5. Handling Non-String Types

ToString(): Requires an object or value type that has implemented a meaningful ToString method. For primitive types, the ToString method is already implemented to return a string representation.
Convert.ToString(): Works with a wide variety of types, providing a consistent way to convert different data types to strings, including DateTime, Boolean, Enum, and numeric types.

6. Culture-Specific Formatting

ToString(): When used with numeric or date types, it can accept culture-specific formatting information through methods like ToString(string format, IFormatProvider provider).
Convert.ToString(): Does not take culture-specific formatting as a parameter directly. However, it uses the current culture settings implicitly, which might not always be desirable.

7. Return Values on Failure

ToString(): Will throw an exception if conversion is not possible, such as calling ToString() on a null reference.
Convert.ToString(): Will return an empty string for null values and will not throw exceptions for most type conversions, making it more robust in error-prone scenarios.

Example Code Illustration

Here’s a simple example to illustrate the usage and differences:

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Step-by-Step Guide: How to Implement Difference Between Convert ToString and ToString in C#

Step 1: Understanding the Basics

Convert.ToString(): This is a static method provided by the System.Convert class. It attempts to convert an object to a string. If the object is null, it returns an empty string (""). It provides more flexibility as it can handle null values gracefully.
ToString(): This is an instance method available to all objects in C#. It is a part of the System.Object class. It converts an object to its string representation. If the object is null, calling ToString() on it will throw a NullReferenceException.

Step 2: Setting Up a C# Console Application

Open Visual Studio (or your preferred C# IDE).
Create a new Console Application project.
Name the project (e.g., ToStringExamples).

Step 3: Writing Example Code

Let's write an example that demonstrates the usage of both Convert.ToString() and the ToString() method.

Main Method

Here's the complete code for the Main method:

using System;

namespace ToStringExamples
{
    class Program
    {
        static void Main(string[] args)
        {
            // Example with a non-null object
            int number = 123;
            string numberStr1 = Convert.ToString(number);
            string numberStr2 = number.ToString();
            Console.WriteLine("Number converted using Convert.ToString(): " + numberStr1);
            Console.WriteLine("Number converted using ToString(): " + numberStr2);

            // Example with a null object
            object nullObject = null;
            string nullStr1 = Convert.ToString(nullObject);
            try
            {
                string nullStr2 = nullObject.ToString();
            }
            catch (NullReferenceException ex)
            {
                Console.WriteLine("Exception caught: " + ex.Message);
            }

            // Print the results of Convert.ToString() when null
            Console.WriteLine("Null object converted using Convert.ToString(): " + nullStr1);

            Console.ReadLine();
        }
    }
}

Explanation

Example with a Non-Null Object:
- We have an integer number with a value of 123.
- We use Convert.ToString(number) and number.ToString() to convert the integer to a string.
- Both produce the same result, which is the string representation of the number "123".
Example with a Null Object:
- We create an object nullObject and set it to null.
- We use Convert.ToString(nullObject) to convert the null object to a string. It returns an empty string ("").
- We try to use nullObject.ToString(), which throws a NullReferenceException because we're attempting to call a method on a null reference.
- We handle the exception and print the error message.

Step 4: Running the Application

Build and run the application.
You should see the following output in the console: