What is the difference between Convert.toString and .toString()

Question

What is the difference between Convert.toString and .toString()

Answer 1

Just to give an understanding of what the above question means seethe below code.
int i =0;
MessageBox.Show(i.ToString());
MessageBox.Show(Convert.ToString(i));
We can convert the integer “i” using “i.ToString()” or “Convert.ToString” so what’s the difference.
The basic difference between them is “Convert” function handles NULLS while “i.ToString()”
does not it will throw a NULL reference exception error. So as good coding practice using
“convert” is always safe.

Answer 2

Hi

There is no difference between i.ToString() and Convert.ToString(i).

This is the body of the Convert method:

public static string ToString(int value)
{
    return value.ToString();
}

Furthermore, the integer variable cannot be null since its a value type.

Answer 3

Kuju wrote:

Hi There is no difference between i.ToString() and Convert.ToString(i). This is the body of the Convert method: public static string ToString(int value) {     return value.ToString(); } Furthermore, the integer variable cannot be null since its a value type.

Kuju is absolutely correct.But what will happen if tostring is to be used with an custom object

Answer 4

Once again using the trusty reflector,  the body of the Convert.ToString(object value)looks like this:

public static string ToString(object value, IFormatProvider provider)
{
    IConvertible convertible = value as IConvertible
    if(convertible != null)
    {
       return convertible.ToString(provider)
    }
    if(value != null)
    {
       return value.ToString();
    }
    return string.Empty
}

Therefore, when you try Convert.ToString() on a custum object, you are guaranteed not to get an ObjectReferenceNullException. On the other hand you might want to get an exception if you don't expect your object to be null.

Answer 5

The difference between Convert.ToString and .ToString() as follows

 

Convert.ToString wont allow null values. Cannot convert null to String

 

Whereas   .ToString accepts null values

 

Thanks,

Srinivasan.K

Sybrant Technologies Pvt. Ltd.,

 

 

Answer 6

Srini,

i think its the other way round

Answer 7

Offcourse there is a difference:

string s;
object o = null;
s = o.ToString();
//returns a null reference exception for s.

string s;
object o = null;
s = Convert.ToString(o);
//returns an empty string for s and does not throw an exception.

Answer 8

Just to give an understanding of what the above question means seethe below code.
int i =0;
MessageBox.Show(i.ToString());
MessageBox.Show(Convert.ToString(i));
We can convert the integer “i” using “i.ToString()” or “Convert.ToString” so what’s the difference.
The basic difference between them is “Convert” function handles NULLS while “i.ToString()”
does not it will throw a NULL reference exception error. So as good coding practice using
“convert” is always safe.

Muhammed Adnan is absolutely correct, so I think it is better using Convert.ToString() than using ToString()...

Answer 9

Muhammed Adnan is correct. 

Answer 10

int number =0;
string strFirst=number.ToString();
string strSecond=Convert.ToString(number );

Here We can convert the integer “number” using “number.ToString()” or “Convert.ToString(number)” . But only the difference between them is “Convert” function handles NULLS while “number.ToString()”
does not handle. It will throw a NULL reference exception error. So as for good programming practice using “Convert” is always safe.

 

Muhammed Adnan is correct.

Thanks

Answer 11

 (1)  ToString() is a method present in the Object class of the System namespace.

Now, Object class is the ultimate base class for all classes in the .NET Framework.So, whenever we create a new class (like Class1), it implicitly extends Object. And it also inherits the ToString() method.

 

         namespace  N1

         {

                       class Class1 : Object                  // implicitly

                       {

                                                                      // inherits the ToString() method

                        }

          }

 

Now, to access the ToString() method in client code, 

 

              Class1 obj = new Class1();                // create an instance of Class1

             Console.WriteLine(obj.ToString());    // call the ToString() method 

                                                                    // We can wrap it in Console.WriteLine() because it returns a string

 

We get the output as :  N1.Class1

Thus ToString() method returns a fully qualified name of the type of the object.

However, we get an error (exception) if we invoke ToString() on a null reference.

 

            Class1 obj = null;                               // obj holds a null value

            Console.WriteLine(obj.ToString());      

We get a null reference exception because we cannot invoke an instance method on a null reference.

In other words  "ToString() method does not handle nulls"

 

(2) Convert.ToString() is a static method present in the static class Convert. BTW, it also extends Object, and inherits the ToString() method.

The Convert class overloads the ToString() method with a set of static methods.

For example, to invoke the ToString(obj), we say:

                   Console.WriteLine(Convert.ToString(obj));   // Convert is a static class, we use the class name to invoke the ToString() method

On executing the above code, the object value is checked for null reference. If it is null, String.Empty is returned. Otherwise, the ToString() method of the Object class is called.

In other words,   "Convert.ToString() handles nulls"

 

 

 

 

 

Answer 12

 ToString() vsConvert.ToString()

We can convert the integer “variable” using “variable.ToString()” or “Convert.ToString” so what is the
difference. The basic difference between them is “Convert” function handles NULLS while
“variable.ToString()” does not it will throw a NULL reference exception error. So as a good coding
practice using “convert” is always safe.

 

Session["your_variable"] ="cheater";

Response.Write(Convert.ToString(Session["your_variable"])); //it will display "cheater"

Response.Write(Session["your_variable"].ToString());//it will display "cheater"

 

 //ERROR will not come in above statement because sesssion contain value

Session["your_variable"] = null;

Response.Write(Convert.ToString(Session["your_variable"])); //it will convert to blank value ,No erro will come

Response.Write(Session["your_variable"].ToString());//will not handle the NULL values and it throws a NULL Reference Exception error

Answer 13

Hi Srini,

you have just made a mistake by answaring the question in.

your ans is:

Convert.ToString wont allow null values. Cannot convert null to String

 

Whereas   .ToString accepts null values

but the correct ans is:

Convert.ToString(str) automatically handle null reference Exception where as if you are using str.ToString(), you need to handle Exception by your code..

You can try the sample code given below

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DifBTConvertToStringAndToStringExample
{
    class Program
    {
        static void Main(string[] args)
        {
            string   iStr=null;
            //throw exception so need to have try catch
            try
            {
                iStr.ToString();// will cause a null ref exception
                throw new Exception("Null ref exe");
            }
            // will not through any exception
            catch (Exception ex)
            {

                Console.WriteLine(ex.StackTrace);
            }
            finally
            {
                Console.WriteLine("I'll be executed in any case"+Convert.ToString(iStr));
            }
        }
    }
}

Answer 14

Convert.ToString() handles null, while ToString() doesn't.

---

PHIJO MP

Answer 15

These reason i know.But any difference rather than this.

Why they are introducing .ToString(); IF any reason.

Answer 16

No sir difference is there.without difference why there are introducing both.only one is enough.Some thing big difference. plz if u know means let me explain one suitchivation.

Not a below reason.

string strValue=nulll;

string valu1=stValue.ToString(); //here is it will return nulllexpection

string vale2=Convert.ToString(strVlaue); //here is it will return null or empty

Answer 17

The basic difference between them is “Convert.ToString(variable)” handles NULL values even if variable value become null but “variable.ToString()” will not handle NULL values it will throw a NULL reference exception error. So as a good coding practice using “convert” is always safe.

//Returns a null reference exception for str.
string str;
object i = null;
str = i.ToString();

//Returns an empty string for str and does not throw an exception. If you dont
string str;
object i = null;
str = Convert.ToString(i);

Source : Here

Answer 18

public static string ToString(object value, IFormatProvider provider)
{
    IConvertible convertible = value as IConvertible
    if(convertible != null)
    {
       return convertible.ToString(provider)
    }
    if(value != null)
    {
       return value.ToString();
    }
    return string.Empty
}

Therefore, when you try Convert.ToString() on a custum object, you are guaranteed not to get an ObjectReferenceNullException. On the other hand you might want to get an exception if you don't expect your object to be null.

Answer 19

string str;
object o = null;
str = o.ToString();//returns a null reference exception for string  str.

string str;
object o = null;
str = Convert.ToString(o);//returns an empty string for string str and does not throw an exception.,it's better to use convert.tostring for good coding