为什么当我编译它时它会抛出一个错误？

Question

在index.hpp中，我创建了一个具有多个数据成员的类，如int age、std::string city；等。我在类外部定义了一个构造函数。在program.cpp中，我创建了一个名为SAM的对象。当我试图编译它时，它显示错误。什么原因？

Program.cpp

#include<iostream>
#include "index.hpp"

int main(){
  profile sam("Sam Drakkila", 30, "New York", "USA", "he/him");
  std::cout<<sam.name;
}

index.hpp

#include<iostream>
#include<vector>

class profile{

public:
    std::string name;
  int age;
  std::string city;
  std::string country;
  std::string pronouns;
  std::vector<std::string> hobbies;

};
profile::profile(std::string new_name, int new_age,std::string 
        new_city,std::string new_country, std::string 
         new_pronouns = "they/them"){
 name = new_name;
 age = new_age;
 city = new_city;
 country = new_country;
 pronouns = new_pronouns;
         }

错误信息

In file included from program.cpp:2:0:
index.hpp:15:1: error: prototype for 'profile::profile(std::__cxx11::string, int, std::__cxx11::string, std::__cxx11::string, std::__cxx11::string)' does not match any in class 'profile'
 profile::profile(std::string new_name, int new_age,std::string
 ^~~~~~~
index.hpp:4:7: error: candidates are: profile::profile(profile&&)
 class profile{
       ^~~~~~~
index.hpp:4:7: error:                 profile::profile(const profile&)
index.hpp:4:7: error:                 profile::profile()
program.cpp: In function 'int main()':
program.cpp:5:62: error: no matching function for call to 'profile::profile(const char [13], int, const char [9], const char [4], const char [7])'
   profile sam("Sam Drakkila", 30, "New York", "USA", "he/him");
                                                              ^
In file included from program.cpp:2:0:
index.hpp:4:7: note: candidate: profile::profile()
 class profile{
       ^~~~~~~
index.hpp:4:7: note:   candidate expects 0 arguments, 5 provided
index.hpp:4:7: note: candidate: profile::profile(const profile&)
index.hpp:4:7: note:   candidate expects 1 argument, 5 provided
index.hpp:4:7: note: candidate: profile::profile(profile&&)
index.hpp:4:7: note: candidate: profile::profile(const profile&)
index.hpp:4:7: note:   candidate expects 1 argument, 5 provided
index.hpp:4:7: note: candidate: profile::profile(profile&&)
index.hpp:4:7: note:   candidate expects 1 argument, 5 provided
 .\index }
index.hpp:15:1: error: prototype for 'profile::profile(std::__cxx11::string, int, std::__cxx11::string, std::__cxx11::string, std::__cxx11::string)' does not match any in class 'profile'
 profile::profile(std::string new_name, int new_age,std::string
 ^~~~~~~
index.hpp:4:7: error: candidates are: profile::profile(profile&&)
 class profile{
       ^~~~~~~
index.hpp:4:7: error:                 profile::profile(const profile&)
index.hpp:4:7: error:                 profile::profile()

Answer 1

我在类外定义了一个构造函数

是的，但您没有在类中声明它。
此外，除非您正在创建模板，否则不应该将代码放在头文件中。

要解决问题,请将声明添加到类中：

class profile{

public:
    profile(std::string new_name, int new_age, std::string new_city, std::string new_country, std::string new_pronouns);

    std::string name;
    int age;
    std::string city;
    std::string country;
    std::string pronouns;
    std::vector<std::string> hobbies;
};

您还应该考虑将构造函数的代码移动到index.cpp，并为清楚起见重命名文件profile.hpp和profile.cpp。