#include <iostream>
cout.precision(10); // 소수점 아래 10자리 까지 출력
Template<class CharT, class Traits > basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>& st, CharT& ch );
After constructing and checking the sentry object, which may skip leading whitespace, extracts a character and stores it to ch.
string str;
getline(cin, str);
cout << str;
char str[100];
cin.getline(str,100,\n); //개행문자 기준으로 입력종료
cout << str;