getline和std :: istream :: operator>>>（）有什么区别？ [英] What's the difference between getline and std::istream::operator>>()?

问题描述

#include <iostream>
#include <string>

using namespace std;

int main()
{
   string username;
   cout<< "username" ;
   cin >> username; 
}

所以我很好奇这两个代码之间的区别，我听说这是同样的事情，但是如果是的话，为什么要用两种方法呢？

So I was curious on what's the difference between these two codes, I heard it's the same thing but if it is then why two ways of doing it then?

#include <iostream>
#include <string>
using namespace std;

int main()
{  
   string username;
   cout << "username" ;
   getline (cin,username) ;
}

推荐答案

区别在于 std :: getline —顾名思义—从给定的输入流（可能是 std :: cin ）和 operator>>中读取 line ; 读取一个单词 ¹ 。

The difference is thatstd::getline — as the name suggests — reads a line from the given input stream (which could be, well, std::cin) and operator>> reads a word¹.

即， std :: getline 读取直到找到换行符，而 operator>> 读取直到一个空格（由定义） std :: isspace ）并找到。两者都从流中删除了各自的定界符，但未将其放入输出缓冲区。

That is, std::getline reads till a newline is found and operator>> reads till a space (as defined by std::isspace) and is found. Both remove their respective delimiter from the stream but don't put it in the output buffer.

^{1。请注意，>> 也可以读取数字— int ， short ， float ， char 等。}

^{1. Note that >> can also read numbers — int, short, float, char, etc.}

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