How does the input operator (>>) know where to stop and take the next input if the inputs are seperated by single spaces?

Question

#include<iostream>

int main()
{
    std::cout << "Enter two numbers:" << std::endl;
    int v1 = 0, v2 = 0;
    std::cin >> v1 >> v2;
    std::cout << "The sum of " << v1 << " and " << v2 << " is " << v1 + v2 << std::endl;
    return 0;
}

If the input given is 5 6, it'll print "The sum of 5 and 6 is 11". But how does the istream know when to stop?

Does it keeps on taking input if its an integer and stops if it gets another data type?

How does it assign the correct values of v1 and v2?

The default delimiter for std::cin is whitespace i.e. your blank. Check this out for additional info. https://stackoverflow.com/questions/7302996/changing-the-delimiter-for-cin-c — TJA, Dec 12 '19 at 06:13
It stops when it reaches the first whitespace after the numbers, that whitespace remains on the stream for future read operations — M.M, Dec 12 '19 at 07:27
@M.M I didn't get what happens to the whitespace. Does it get flushed? — Deepak Pawade, Dec 12 '19 at 09:22

score 4 · Answer 1 · answered Dec 12 '19 at 06:21

4

(>>) is an extraction operator. It can be used more than once to accept multiple inputs. It differentiates the multiple inputs through spaces or the next line. In your case, there is a space between 5 and 6 so the extraction operator will assign 5 for v1 and 6 for v2.

answered Dec 12 '19 at 06:21

Rishabh Singh

41
2

yes, The default delimiter for std::cin is whitespace. Thanks for answering though! – Deepak Pawade Dec 12 '19 at 06:23

How does the input operator (>>) know where to stop and take the next input if the inputs are seperated by single spaces?

1 Answers1