i dont understand the use of cin

[dynamo]

In the following program i dont how cin knows where day, stops and ch ,starts.
The same thing for month and year. When you type the input string without spaces.Can anyone help?thanks

#include <iostream.h>
int main (void)
{
int day, month, year;
char ch;
cout << "Input a date as dd/mm/yy: ";
cin >> day >> ch >> month >> ch >> year;
switch (month) {
case 1: cout << "January"; break;
case 2: cout << "February"; break;
case 3: cout << "March"; break;
case 4: cout << "April"; break;
case 5: cout << "May"; break;
case 6: cout << "June"; break;
case 7: cout << "July"; break;
case 8: cout << "August"; break;
case 9: cout << "September";break;
case 10: cout << "October"; break;
case 11: cout << "November"; break;
case 12: cout << "December"; break;
}
cout << ' ' << day << ", " << 1900 + year << '\ n';
return 0;
}
 

[azzmosphere]

I tried to compile this program using the following syntax:

g++ filename.c -o filename

Mainly because I couldn't see how it would work. C++ describes cin and cout as being able to split on a valid decimeter which it describes as a "a space, a tab character or a newline". Therefore the syntax:

cin >> day >> ch >> month >> ch >> year;

would not work on the at least the compilers that I use. In order to get this program to function you would need to enter an input string such as:

12 / 11 / 08 no 12/11/08

[Ganon11]

Correct. The >> operator, when used with cin, uses whitespace to separate what are parsed as tokens. So if you enter 05/11/1989, the entire string will go into month. You need to ask your user to enter the string with spaces (i.e. "05 11 1989"), or you need to read the whole string ("05/11/1989") into a single string, then break up the string yourself (using the .substr() functio).

[boxfish]

(using the .substr() functio).

Or maybe strtok... ?

[boxfish]

No, wait a minute. There's nothing wrong with the code there and the program works just fine. No need for breaking up the string yourself. When you cin into an integer variable such as day, cin skips over all leading whitespace, and then reads into day until it encounters a character that is not a digit, such as a /. It knows to stop as soon as it hits a non-digit, even if it isn't whitespace.
Hope this helps.

[dynamo]

Thanks for the help guys it feels so good to be part of a community with so many brilliant minds.I think the last reply explains everything thanks again.