Using `getline(cin, s);` after using `cin >> n;`

问题:

int n;
std::cin >> n;

std::string s = "";
std::getline(cin, s);

I noticed that if I use cin, my program would hang the next time I reach the line getline(cin, rangeInput).

Since getline() is using cin, is that why it is causing the program to hang if I have previously used cin? What should I do if I want to get a line after using cin?

回答1:

You need to clear the input stream - try adding the following after your cin:

cin.clear();
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

The accepted answer to this question gives a good explanation of why/when this is required.

回答2:

std::cin leaves an extraneous \n in the input stream. When you use std::getline(), you are retrieving that \n.

Although @WilliamLannen's answer works if you really need std::cin, you are better off using this method:

int n;
std::string sn;
std::stringstream ssn;

std::getline(std::cin, sn);
ssn << sn;
ssn >> n;

---

References

http://www.daniweb.com/software-development/cpp/tutorials/71858

回答3:

int n;
std::cin >> n;


std::cin.get() //<--- use cin.get() here ...


std::string s = "";
std::getline(cin, s);