oop - work with different files in c++ -

hello have simple program main.cpp a.h , a.cpp. i'd define class in a.cpp , call on method of class in main.cpp

my a.h:

#include <iostream> using namespace std;  class hello  {  string hello(); }; 

my a.cpp

#include "a.h" #include <iostream>  string class hello::hello(){return "hello world";}; 

my main.cpp

#include "a.h"   int main()  {   hello h;   cout << h.hello();    } 

edit : changed include"a.cpp" a.h , added string definition of method hello. added #include <string> a.h

while compiling error

"a.cpp:4:22: error: ‘hello’ in ‘class hello’ not name type string class hello::hello() {return "hello";};"

"a.cpp:4:28: error: expected unqualified-id before ‘)’ token string class hello::hello() {return "hello";};"

a simple problem, have declared function part of class:

class hello { // ^function part of class hello.  string hello(); // ^function returns string //      ^function called "hello" //           ^function takes no arguments. 

so when go define function need give compiler same information:

string hello::hello() { // ^function returns string //      ^function part of class hello //             ^function called "hello" //                  ^function takes no arguments.    

• you need add header <string> file facilitate use of string object.
• your '#include "a.cpp" needs #include "a.h", rule of thumb should never ever see #include file.c/cpp.
• finally, need make function hello public allow use outside class members.

here live example play with.

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