比较字符串不适用于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;
}

Answer 1

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()

Answer 2

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)