Compare string doesnt work with cin

Question

I am working on a trivial problem, but I cant figure it out. The program should put out the part after "simon says" if the beginning of str1 is "simon says". if i run it like in the following code, it works, but if i enter the string over cin >> str1; myself, it doesnt. Does anybody have a tip for me? (and yes, this is a kattis problem)

int main() { string str1("simon says write a program"); //cin >> str1; string str2 ("simon says"); if (str1.compare(0,10,str2,0,10) == 0){ cout << str1.substr(11,str1.size()); } return 0; }

>> extracts whitespace-separated tokens. This is not the construction you are looking for. — Kerrek SB
– Kerrek SB, Commented Jul 21, 2015 at 12:23
You should print str1 after cin << str1, you can see that the string contains only simon. — alifirat
– alifirat, Commented Jul 21, 2015 at 12:25
I think you have got the answer you are looking for. So why don't you close the question. — Anony-mouse
– Anony-mouse, Commented Jul 21, 2015 at 12:26

Blood · Accepted Answer · 2015-07-21 12:24:09Z

It's because std::cin gets whitespace-separated strings. If you will try to read a string from the standard input using

std::cin << str1; // something here std::cin << str2;

And you will enter "simon says", "simon" will land in the str1 and "says" will go to the str2. To read a whole line you should use

std::getline()

alifirat · Accepted Answer · 2015-07-21 12:27:17Z

With using cin >> str1, if you print str1 for the sentence "Simon write something", you will see that str1 has the value "Simon".

To not cut the sentence to the first space, Replace cin >> str1 by getline(cin, str1)

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