I dont get good answers on google. Does anyone know why there is a computational error when a string is used to store a numerical value then it is converted to a number data type and it produces an error in the value?

I remember having a discussion with one of my math peers about floiting point error but it seems different than that. For example in c++

#Include <iostream></iostream>

#Include <cmath></cmath>

Using namespace std

Int main ()

{

\ declaration of string value

string X=" "

\ ui to get an input

cout << "Enter a numerical value";

cin >> X;

cout << "\n" << endl;

*conversion, redeclaration with associated values *\

const double pi =3.1415

double stragcel = stof(X) * pi * 2

\ print of your cute twinkry

cout << "The amount of cute twinkry in your soy titties is " << stragcel << " inches squared. You might wanna get that checked out." << " In terms of the range of the oscillations of your cute twinkry it is " << sin(stragcel) << " to " << sin(-stragcel) << ". This is dangerously off the charts. We cannot help your cute twinkry, sir." << endl;

return 0;

}I have done similar things with floating points but the error seems to be constant with int, float, and double. What is it?