Part 59 C# Tutorial Difference between Convert ToString and ToString Video

hello welcome to prism technologies I am
venket this is pod 59 in this session
we'll understand the difference between
convert the two string method and two
string method let's understand that with
an example in this program you see a
very simple customer class that has just
got a name property now to create an
instance of this class with a customer
c1 is equal to new customer now to get
the string representation of this C 1 we
can use dot to string method so C 1.2
string so when we do that we get the
string representation of this customer
object so let's create a string variable
to hold that
let's call string STR alright if we want
to print that we can say console dot
write line STR and if you remember in
the previous session we have discussed
about the importance of overriding the
to string method you know if you want
something meaningful out of this string
representation of a specific object then
we override the to string method but
here we haven't overridden the to string
method okay by the way where is this two
string method coming from it's coming
from the basic system object class and
we haven't overridden that so obviously
when we try to run this what do we get
back we get back you know the complete
type name you know including the name
space okay that's the default
implementation that's available in
system dot object base class all right
so to get the string representation of
this customer object there is another
way now instead of using two string we
can use the convert class so convert dot
in this class we have a static method to
string you can use that and pass the
object okay now when I run that and
obviously in the output you wouldn't see
any difference okay you get the same
output okay but the difference is when
this customer object reference variable
is null for some reason okay if you are
passing this as a parameter to a method
and you don't initialize that or this
object is not created for some reason
you know it is possible that it could be
null at times okay so if it is now and
when I use the to string the static to
string method in the convert class you
know what actually happens is let's put
a breakpoint here when we run this so if
you look at this c1 is now so when you
pass a null object to the to string
method in the convert class it actually
converts that even null in to an empty
string look at that STR is an empty
string okay but on the other hand if we
use two string method on the object C
1.2 strain what's gonna happen let's see
let's run this when you run this what
happens look at this we already got a
null reference exception and that's
because look at that c1 is now and on
that null you're trying to call this
instance two string method so on a null
object okay you cannot call an instance
method so that's why we get a null
reference exception and it makes sense
and you look at the error message null
reference exception object reference not
set to an instance of an object which
means this reference variable is not
pointing to any instance of the object
on the heap okay so very simple
difference between convert or to string
and two strings so what's that convert
not to string handles nulls and return
an empty string if the past in object is
now but whereas the to string method
doesn't handle nulls and it throws an
exception what type of exception null
reference exception why because animal
object you're trying to convert to a
string so we get a null reference
exception back okay but you cannot say
one method is better over the other
depending on the type of the application
the architecture of that application and
what you're trying to achieve you choose
one over the other for example if you're
designing a class library and you expect
a property to be initialized or you
expect the object to be you know
pointing to some concrete object on the
heap and if you if users the client cool
if the client low doesn't pass in that
object then it makes sense to do an
exception but in the UI you don't want
to be throwing an exception on the UI
part you just want to you know print the
error message to the user in that case
probably you use you know the conversion
or to stream just in case if it happens
to be at now you know we can check if
it's an empty string using convert or to
string and then display an appropriate
error message on the UI to the user so
depending on the type of the application
architecture and what you're trying to
achieve you choose one or the other
we cannot say one is better over the
other on this slide you can find
resources for asp.net and C sharp
interview questions that's it for today
thank you for listening have a great day