C# Programming - Classes and Objects - Discussion

If you run this program using "this" keyword the answer becomes 10 and 5.4 and them how come zero?

Actually it works just like the "ref" and "out" type variables, when you type :

this.varialblename

The variable references to the variable in the constructor.

Here don't use this keyword that's why does not takes values for example if u take this.i and this.j in setdata then u will print some values so output is 0 0.

The code is write is perfect but the on the time of value initialization it's initializing himself rather than to the variable declares in the class. Have a look in the below snippet.

class Sample
{
int i;
Single j;
public void SetData(int i, Single j)
{
this.i = i;
this.j = j;
}
public void Display()
{
Console.WriteLine(i + " " + j);
}
}

It is because the s1.SetData(10, 5.4f); will set the values if i, j but in line s1.Display(); function will call default constructor and default values assigned to i,j (0,0) .

That is why it will print 0 0.

Here in the above:

public void SetData(int i, Single j)
{
i = i;
j = j;
}

We are trying to assign the value to the local variable that is,
i=i;
j=j;
So to resolve this problem we should write like :

public void SetData(int i, Single j)
{
this.i = i;
this.j = j;
}

This is an object of current class ,when the function call like:
sample obj1=new sample();

Then 'this' object contains the address of obj1 and now this directly referred to the object to obj1 and now it will store the value into the data field of object.

class Sample
{
int i;
Single j;
public void SetData(int i, Single j)
{
i = i;
j = j;
}
public void Display()
{
Console.WriteLine(i + " " + j);
}
}

In the above code we are using local variables with same name as instance variable, because local variable will hide the instance variable. Instance variables will not get initialize. To refer the instance variable in case of local variable name is same as instance variable, use this keyword.

like this.i = i; //here this.i refer to instance variable i.

Assignment should done to the different variables.

That's why it is printing default var 0 0?

0 0 are default values set by constructor when object gets created.

Due to the naming collision more than having to use the this keyword as proper syntax.