c++ - Undefined variables within header files -

thanks taking time view question. i've spent lot of time looking can't find solution problem:

i have class person its' respective header file person.h. cpp class having hard time understanding variables name, age, , iq are.

//person.cpp  /* makes person. person has name, age, , iq level. create many of these objects within other classes. */  #include "person.h"  person::person() //empty constructor {  } person::person(string thename, int theage, int theiq) {     name = thename;     age = theage;     iq = theiq; }  string getname() {     return name; //error: identifier "name" undefined }  int getage() {     return age; //error: identifier "age" undefined }  int getiq() {     return iq; //error: identifier "iq" undefined }  void setname(string aname) {     name = aname; //error: identifier "name" undefined }  void setage(int aage) {     age = aage; //error: identifier "age" undefined }  void setiq(int aiq) {     iq = aiq; //error: identifier "iq" undefined } 

the header file

//================================= // include guard #ifndef __person_h_included__ #define __person_h_included__  //================================= // forward declared dependencies   //================================= // included dependencies #include <string> //for name   //=================================  using namespace std;  class person { public:     person(); //default constructor     person(string thename, int theage, int theiq); //constructor     string getname();     int getage();     int getiq();     void setname(int aname);     void setage(int aage);     void setiq(int aiq);  private:     string name;     int age, iq; };  #endif //__person_h_ 

surely don't have define variables inside person.cpp right? knows variables name, age, , iq because saw header file already. why can not understand variables are?

if do, or if there i'm missing, make sure spell out me. i'm barely intermediate c++ programmer may not understand jargon. things scope, inheritance, , definitions go way on head.

thank time.

to ever part you're getting errors this: return type person::function name(parameters)

for declaration part of functions.

for example getage function this:

int person::getage() {       return age; } 

the reason got errors because of following:

1. first intention define functions declared in person class.
2. in return statement wanted return age member of person class. returned age.
3. the search age begins inside function body first. if not found searched in outer scope. if still not found age unknown identifier.

after fix happens this:

1. the person:: part in return type person::function name(parameters) means in scope of person class.
2. then in return statement return age member of person class. time we're looking inside scope of person class, hence return age member , error fixed.