to get data type

[gautam jha]

suppose I have some variable name and I don't know its data type how I will know its data type. And if I have two variable names then how I will compare if their data type is same or not.

[quirkyusername]

in what situation would you not know an object's data type? Other than passing a void* and there are few situations which warrant that.

[Moschops]

http://www.cplusplus.com/reference/std/typeinfo/type_info/

[CrazyBoy]

use Library Function : typeid(variable name).name()

[ne555]

Agreed with quirkyusername.
Besides, you still know the type of a void *, it is of type void *