basic (i think) c++ .h error

nadroj · 10-21-2005, 06:54 PM

im working on a very simple c++ program...
i have a header file, as follows:

Code:

#include <iostream>
#include <string>

#ifndef JI_PhoneHeader
#define JI_PhoneHeader

using namespace std;

struct PhoneEntry
{
       string name;
       long phoneNumber;
};

enum SortingType {name, number};

class PhoneBook
{
      PhoneEntry entries[100];
      SortingType sortBy = name;
  
}

#endif

i get this error:

Quote:

Line 22 : ISO C++ forbids initialization of member `sortBy'

it then says that it will make 'sortBy' static... then gives an error about it being static, lol
this is my first header file, so im sure im doing something basic wrong.

any help appreciated.

spooon · 10-21-2005, 07:00 PM

I think you should do the initialization in a constructor, i.e.

Code:

class PhoneBook
{
      PhoneEntry entries[100];
      SortingType sortBy;
public:
      PhoneBook() { sortBy = name; }
}

nadroj · 10-21-2005, 07:33 PM

alright, thanks for the help..
however, i still get an error.. but it doesnt point to the header file.. but i think it still has something to do with it, since my tester file basically has nothing in it TO have an error.
heres the file that uses the header (i simply made it so it could complie the header):

Code:

#include "PhoneHeader.h"
#include <iostream>
#include <string>

using namespace std;

int main()
{
}

it says "Line 5 : expected unqualified-id before "using" "
and "Line 5 : expected `,' or `;' before "using" "

edit: im in window$ so i dont actually need to return something, so thats not the problem

dmail · 10-21-2005, 07:45 PM

have you added a semi colon to the end of the class ie

Code:

class PhoneBook
{
      PhoneEntry entries[100];
      SortingType sortBy;
public:
      PhoneBook() { sortBy = name; }
};

also i would include iostream and string after the ifndef, it wont make any diff to this code (edit it will, it will mean you dont have to declare them in the main cpp file) but when you have a header which is included in multiple files it ensures they are not included everytime.

Code:

#ifndef JI_PhoneHeader
#define JI_PhoneHeader

#include <iostream>
#include <string>

actually ansi requires that you return an int from main.

nadroj · 10-21-2005, 07:51 PM

perfect.. thanks.

im not used to c++, and this is my first class and header i have ever made..
i normally use java, and you dont make classes the same way.. and dont need the end-of-statement semicolon after declaring a class.

i see what you mean about the (possibly) duplicate #include statements. thanks

nadroj · 10-21-2005, 08:34 PM

i cant belive i cant figure this out and how i cant apply my java knowledge to do it!

well, heres the code for a class i have declared in a header file:

Code:

class PhoneBook
{
      const int max = 100;
      PhoneEntry entries[];
      int next;
      
      SortingType sortBy;
      
public:
      PhoneBook()
      {
      sortBy = name;
      next = 0;
      }
};

but i get the same error as before.. '19 : ISO C++ forbids initialization of member `max' '
so i remove the ' = 100' and add 'max = 100;' to the phonebook constructor.. then.. obviously it gives error saying i cant set the value for max because its const (of course).
doing it the way just described, but removing the const, works.. but i need it to be const.
any hints?

it seems that you cannot initialize any variable outside of a function?

dmail · 10-21-2005, 08:39 PM

for it to be initailised inside the class like you have done it, it would have to be a static const int
see http://www.devx.com/tips/Tip/5602

nadroj · 10-21-2005, 08:43 PM

alright..
i read the tip.
it works, thanks again...untill my next question

looks like i have alot to learn with classes in c++.. even after studying java for afew years and being very comfortable with it.

nadroj · 10-21-2005, 10:02 PM

here i come

ok...

in my header file, i have an enum as follows:

Code:

enum SortingType {name, number};

i also have a simple function in the header to change the 'sorting type':

Code:

void changeOrder(SortingType sort)
      {
           sortBy = sort; // sortBy is of type SortingType
      }

in another program, i have an object of this type of class ('PhoneBook'). i am trying to access the changeOrder function to change the type of sorting used, ie:

Code:

myPhoneBook.changeOrder(SortingType);

where SortingType is obviously some data of that type.
in my testing program i also have a string called name and an integer called number... therefore, i cannot use the enumerated value of 'name' to specify the SortingType, ie:

Code:

myPhoneBook.changeOrder(name);

because it is a string, and doesnt know which 'name' im talking about.

how can i access the enumerated value?

i have tried things such as 'PhoneBook.SortingType.name', 'myPhoneBook.SortingType.name' etc

i also tried just specifying 0 or 1.. because enums are basically conts' with integer values i though.. but it doesnt work.

thanks for any help, again.

dmail · 10-21-2005, 10:32 PM

Code:

void changeOrder(SortingType sort)
      {
           sortBy = sort; // sortBy is of type SortingType
      }

this func needs to be part of the class interface

like

Code:

class PhoneBook
{  
public:
      PhoneBook()
     {
      sortBy = name;
      next = 0;
      }
      void changeOrder(SortingType sort){ sortBy = sort; }
private:
      static const int max = 100;
      PhoneEntry entries[];
      int next;
      SortingType sortBy;
};

by having the func implentation in the class definition you are inlining it (which is ok), but normally when you have more complicated funcs there are implemented in the corrisponding .cpp

example:
in the .h

Code:

class PhoneBook
{  
public:
      PhoneBook();
      void changeOrder(SortingType sort);
private:
      static const int max = 100;
      PhoneEntry entries[];
      int next;
      SortingType sortBy;
};

in the .cpp file

Code:

#include "enter_header_name_here.h"

//constructor
PhoneBook::PhoneBook()//note :: is the scope operator
{
       sortBy = name;
      next = 0;
}

//setter for the sort type
PhoneBook::changeOrder(SortingType sort)
{
       sortBy = sort;
}

as a additonal note i declare any varibales which are part of the class as:
m_variable_name;
which makes it nicer to do things like

Code:

 
//setter for the sort type
PhoneBook::changeOrder(SortingType sort)
{
       m_sort = sort;
}

to access the sortBy create a getter func

Code:

class PhoneBook
{  
public:
      PhoneBook();
      void changeOrder(SortingType sort);
      SortingType get_sort() { return sortBy; }
private:
      static const int max = 100;
      PhoneEntry entries[];
      int next;
      SortingType sortBy;
};

nadroj · 10-21-2005, 10:39 PM

first.. thanks alot!

sorry.. i didnt want to paste all of the code, but yes, the function is defined in the public: portion of the class declaration.
would it make a difference if i put the enum declaration inside of the class?

also.. are you saying i have to override (well i guess not override.. but define) the changeOrder function in my actual program/tester? i shouldnt HAVE to do that just to access the values in my enumerated type, correct?

thanks again..

edit:
for example.. the beginning part of my .h file is:

Code:

using namespace std;

struct PhoneEntry
{
       string name;
       long phoneNumber;
};

enum SortingType {name, number};

class PhoneBook
{
      static const int max = 100;
      PhoneEntry entries[max];
      int next;
      // ..... etc etc, public declarations follow...

(if that helps at all :S)

dmail · 10-21-2005, 10:54 PM

Quote:

Originally posted by nadroj

first.. thanks alot!

sorry.. i didnt want to paste all of the code, but yes, the function is defined in the public: portion of the class declaration.
would it make a difference if i put the enum declaration inside of the class?

yes, as it is the enum is global in the file scope.

Quote:

also.. are you saying i have to override (well i guess not override.. but define) the changeOrder function in my actual program/tester? i shouldnt HAVE to do that just to access the values in my enumerated type, correct?

thanks again..
you dont have to, like i said if its in the header file where the class is then its inlined, but you dont normally put it there(unless its a getter/setter like this is

)

Quote:

for example.. the beginning part of my .h file is:

Code:

using namespace std;

struct PhoneEntry
{
       string name;
       long phoneNumber;
};

enum SortingType {name, number};

class PhoneBook
{
      static const int max = 100;
      PhoneEntry entries[max];
      int next;
      // ..... etc etc, public declarations follow...

(if that helps at all :S) [/B]

so using this code if you wanted to find the name field in the PhoneEntry
first call the getter (Phone.get_entry(index) ) and then offset to the string giving
Phone.get_entry(0).name;

Code:

string the_name;
PhoneEntry (Phone);//creates the class
the_name = Phone.get_entry(0).name;//see below

Code:

PhoneEntry PhoneBook::get_entry(int index)
{
      if(index >= max)
      {
             //handle the error here
             ;
      }
      else return entries[index];
}

nadroj · 10-21-2005, 11:01 PM

for my question regarding if it would make a difference if i put the enum declaration inside the class.. i know its global now, and would then only be accessible inside the class (as private) if i put it in there..
i was really asking if putting the enum in there would some how solve the problem i am having?

i wouldnt think so..

but my question is still regarding how, in my tester program, access the values in my enum SortingType (ie name and number).

dmail · 10-21-2005, 11:04 PM

using the get_entry func
like
Phone.get_entry(index).name;
Phone.get_entry(index).PhoneNumber;

hmm you confused me here having a string name and an enum

could you clarify what you mean by

Quote:

...access the values in my enum SortingType (ie name and number).

hmm i think it would be easier to do this if you sent me your files so i could have a look dmail00@gmail.com

nadroj · 10-21-2005, 11:12 PM

ok.. that function gets a specific PhoneEntry.. i dont need that.
well, i actually already have a 'find' function. that isnt the quesion though

in my tester program (.cpp) i have the following bits of code:

Code:

//...
PhoneBook pb;

/* ...   some code later, i want to use my display() method (public, declared 
in the PhoneBook class) i have to display a list of all phoneEntries.. the 
display method relies on a member in the PhoneBook class called sortBy. 
this is of type SortingType (an enumerateed type in my .h) it can be 
either 'name' or 'number'. if its name, the list will be displayed 
alphabetically.. if 'number' then it will be displayed in order of ascending 
numbers or whatever.
*/
pb.changeOrder(X);
/* X needs to be of type 'SortingType' (again, the enum defined in my .h).. 
say i wanted to set it to the enumerated value declared 'name'.. what
 would i type in place of X?! just typing 'name' wont work.. i have tried 
typing random things like 'PhoneHeader::SortingType.name'  etc
*/

hope its more clear now

thanks

edit:
ill try and describe it very simply, and without names or anything related to the above information:
i want to access a value for an enumerated type in a file other than the one it is declared in.

hopefully that makes sense...

- in one file (.h) i have an enum (enum SortingType {name, number}; )
- in another file (.cpp), i need to specify a value for something of type 'SortingType'.. say the enumerated value for 'name'..
how do i do that?