promp the user for invalid input

[davez]

float num;
cout<<"Enter Number: ";
cin>>num;

now what i need to is to display an invalid input if the user inputted a number with decimal.

[MiiNiPaa]

You need to read number and display an error if it is not whole?

Check if number stays same after truncation:

if (num != std::trunc(num))
  //ERROR 

[davez]

is it possible if i will not use math.h

[MiiNiPaa]

if (num != static_cast<int>(num))