C/C++ counting the number of decimals?

Question

Lets say that input from the user is a decimal number, ex. 5.2155 (having 4 decimal digits). It can be stored freely (int,double) etc.

Is there any

Answer 1

What do you mean "stored freely (int"? Once stored in an int, it has zero decimals left, clearly. A double is stored in a binary form, so no obvious or simple relation to "decimals" either. Why don't you keep the input as a string, just long enough to count those decimals, before sending it on to its final numeric-variable destination?