Question

I’ve put together a simple C++ "Hello World" program to practice; unfortunately, upon compilation I get a few errors:

expected ‘)’ before fName

error: prototype for ‘HelloWorld::HelloWorld(std::string, std::string)’ does not match any in class ‘HelloWorld’

Below is my code, can anyone help me understand what I’m missing/overlooking? Thanks.

Header:

  1 #ifndef HELLOWORLD_H_ 
  2 #define HELLOWORLD_H_
  3 #include <string>
  4 
  5 class HelloWorld
  6 {
  7     public:
  8         HelloWorld();
  9         HelloWorld(string fName, string lName);
 10         ~HelloWorld();
 11 };
 12 
 13 #endif

Implementation:

  1 #include <iostream>
  2 #include <string>
  3 #include "HelloWorld.h"
  4 
  5 using namespace std;
  6 
  7 HelloWorld::HelloWorld()
  8 {
  9     cout << "Hello, anonymous!";
 10 }
 11 
 12 HelloWorld::HelloWorld(string fName, string lName)
 13 {
 14     cout << "Hello, " << fName << ' ' << lName << endl;
 15 }
 16 
 17 HelloWorld::~HelloWorld()
 18 {
 19     cout << "Goodbye..." << endl;
 20 }

Answer 1

You need to change your header file to reference std::string instead of string because they are defined inside the std namespace.

HelloWorld(std::string fName, std::string lName);

It works in your .cpp file because you specifically import this namespace. The solution however is not to import this namespace in your header file (generally speaking a bad idea in C++).