C++ 主题 : Using "getline" in conjunction with "If If else"

Question

我有一个关于将 getline 与 If/Else If 语句一起使用的问题。

目前，我的代码如下所示:

    int yourAge = 13;

        cout << "What's your age dude? ";

           if(yourAge < 21) {

        cout << "What? " << yourAge << "? You're too young to drink!!! " << endl;

         } else if(yourAge >= 21) {

         cout << "Cool!" << yourAge << "? You are good to go.  Don't drink    and drive!" << endl;

      }
        return 0;

  } 

这很好用。 yourAge 是 13，结果是它说“你太年轻了不能喝酒”。

不过，我想在代码中引入getline函数，让结果取决于用户的输入。我试图更改代码如下:

      int yourAge;

      cout << "What's your age dude? ";

       getline(cin, yourAge);

        if(yourAge < 21) {

       cout << "What? " << yourAge << "? You're too young to drink!!! " << endl;

} else if(yourAge >= 21) {

    cout << "Cool!" << yourAge << "? You are good to go.  Don't drink and drive!" << endl;

}

return 0;    
   }

这反过来会导致每当我尝试编译时出现此错误消息:

  "ctut.cpp: In function ‘int main()’:
   ctut.cpp:25:25: error: no matching function for call to        ‘getline(std::istream&, int&)’
 getline(cin, yourAge);
                     ^
   ctut.cpp:25:25: note: candidates are:
   In file included from /usr/include/wchar.h:90:0,
             from /usr/local/include/c++/4.9.2/cwchar:44,
             from /usr/local/include/c++/4.9.2/bits/postypes.h:40,
             from /usr/local/include/c++/4.9.2/iosfwd:40,
             from /usr/local/include/c++/4.9.2/ios:38,
             from /usr/local/include/c++/4.9.2/ostream:38,
             from /usr/local/include/c++/4.9.2/iostream:39,
             from ctut.cpp:1:
  /usr/include/stdio.h:442:9: note: ssize_t getline(char**, size_t*, FILE*)
  ssize_t getline(char ** __restrict, size_t * __restrict, FILE *    __restrict)      __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_4_3);....." 

这只是开始，它会持续很长一段时间。

任何有关如何修改的帮助将不胜感激。我想让用户输入有关用户年龄的信息，并根据输入在屏幕上显示正确的消息。

谢谢!

Answer 1

引用 cppreference.com ,

getline reads characters from an input stream and places them into a string.

因此，只有当您的变量 yourAge 是 std::string 时，getline() 才会起作用。对于读取 int，std::cin 就足够了。