Calculator Application without GUI

[GCK]

I am trying to write code for a calculator in a way it appears in GUI.What i mean here is ,i want to display a zero and then replace it with a value (typed) there after perform operations.I am using Visual Studio 2010 ,i want my output to appear as explained above in the Output window of visual studio.

Is there any KEYWORD in C++ (may be advanced C++) to replace a value or variable??

Lastly, is my question right??
Can this be done on the console window of visual studio ??

[gelatine]

cout<<0<<endl;
cls(); 
or system("cls");
//cleans screen
cout<<newvalue<<endl;

[GCK]

Hi gelatine,

Clearing the screen ,ya that's fine thanks :)

but, firstly i would like to see 0 being printed and then it getting replaced with a value ..
I don't see any output :(
neither ' 0' nor the newvalue (i declared the newvalue and used cin )

Its not working ...:(