confused with cin in C++

[John Ruan]

This is a small program in C++. I want to try to type in real number instead
of integer to see how the program runs.
And I am confused. If I input integer for both variables, the program runs
fine. But if I input a real number for the height (like 68.2), the second
cin doesn't work at all!!

I expected any real number will be truncated and that is my only
expectation. But it seems that there are other problems. Can anybody try it?



#include <iostream>
using namespace std;

int main(void)
{
const double INCHES_PER_METE R = 39.37;
const double POUNDS_PER_KG = 2.24;

int height;
int weight;

cout << "METRIC CONVERTER" << endl << endl ;
cout << "Enter your height in inches " ;
cout << "(No fractions, please!) : " ;
cin >height;

cout << "Enter your weight in pounds" ;
cout << "(No fractions, please!)" ;
cin >weight;
cout << endl ;

double metric_height = height/INCHES_PER_METE R;

double metric_weight = weight/POUNDS_PER_KG;


cout << "Your height is " << metric_height << " meters." << endl;
cout << "Your weight is " << metric_weight << " kilograms." << endl;

return 0;
}

[Bo Persson]

Re: confused with cin in C++

John Ruan wrote:

This is a small program in C++. I want to try to type in real
number instead of integer to see how the program runs.
And I am confused. If I input integer for both variables, the
program runs fine. But if I input a real number for the height
(like 68.2), the second cin doesn't work at all!!
>

The input is originally text, which is scanned for digits that can be
part of an integer. The first input reads a 6 and an 8, and gives you
the number 68.

When you try to read a second integer, the first character found is a
period, which is an error for integers. You get no number.



Bo Persson