1、cin.getline函数属于std::istream类

其用法：

istream& getline (char* s, streamsize n );
istream& getline (char* s, streamsize n, char delim );

s：存储读取的数据。

n：读取数据的数量

delim：指定行结束符，默认是'\n'

// istream::getline example
#include <iostream>     // std::cin, std::cout

int main () {
  char name[256], title[256];

  std::cout << "Please, enter your name: ";
  std::cin.getline (name,256);

  std::cout << "Please, enter your favourite movie: ";
  std::cin.getline (title,256);

  std::cout << name << "'s favourite movie is " << title;

  return 0;
}

2、std::getline (string)

istream& getline (istream& is, string& str, char delim);
istream& getline (istream& is, string& str);

// extract to string
#include <iostream>
#include <string>

int main ()
{
  std::string name;

  std::cout << "Please, enter your full name: ";
  std::getline (std::cin,name);
  std::cout << "Hello, " << name << "!\n";

  return 0;
}

注：这两个函数属于不同类。即是不同的函数，同名而已。