String concatenation in c++

Question

Why this code outputs "Hi!This!" if user input is "This is string"

string s;
cin>>s;
s="Hi!" + s + "!";
cout<<s;

Answer 1

If you replace
cin >> s:
with
getline(cin, s);
it also supports full names.

Answer 2

cin extraction always considers spaces (whitespaces, tabs, new-line...) as terminating the value being extracted, and thus extracting a string means to always extract a single word, not a phrase or an entire sentence.

To get an entire line from cin, there exists a function, called getline, that takes the stream (cin) as first argument, and the string variable as second.