Help with modules!

[Moe45673]

I'm in a course called intro to C++ for C programmers, so I already have a basic grasp of C programming and am a few weeks into C++. We have to work with files and have an assignment that gives us a main() program. We have to use the instructions to provide the definitions for the functions so the main() program works, by creating a header and a .cpp implementation. Standard stuff.

Anyhow, I commented out all the stuff in the main() except the stuff about opening and closing a file. There's a function there whos prototype is
FILE* open(const char filename[]);

In other words, the main program is calling this function with similar syntax to this.
open("file.txt");

I define it in my .cpp as
FILE* open(const char filename[])
{
FILE *fp;

fp=fopen(const *filename, "r");

return fp;
}

For reference, here are all my includes in the cpp file. The .h file has just the prototypes and a struct variable (which I haven't used yet).

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
#include "ISBNPrefix.h"



here is the compile time error:
g++ main.cpp ISBNPrefix.cpp
In file included from main.cpp:14:
ISBNPrefix.h:14: error: expected initializer before '*' token
main.cpp: In function 'int main()':
main.cpp:27: error: 'open' was not declared in this scope
main.cpp: At global scope:
main.cpp:84: error: expected unqualified-id before 'return'
main.cpp:85: error: expected declaration before '}' token
In file included from ISBNPrefix.cpp:11:
ISBNPrefix.h:14: error: expected initializer before '*' token
ISBNPrefix.cpp: In function 'FILE* open(const char*)':
ISBNPrefix.cpp:17: error: expected primary-expression before 'const'


Any more info or anything that needs to be clarified, please let me know! Halp!

[tolga gerekci]

return fp not *fp

[Moe45673]

Cheers, did that. Edited my code to include new compile errors, return fp not *fp, and
#include <cstdio>

Update?

I should add that in the compile errors, the line that references line 14 in ISBNPrefix.h is referring to the prototype for that function in the header.

EDIT

Ok, I took away the "const *" from the fopen() call. That helped a bit

Also, I was an idiot in the way I commented out the code in the main() file. Fixed that.

Now looks like:

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

#include "ISBNPrefix.h"

FILE* open(const char filename[])
{
FILE* fp;

fp=fopen(filename, "r");

return fp;
}


New compile errors:

g++ main.cpp ISBNPrefix.cpp
In file included from main.cpp:14:
ISBNPrefix.h:14: error: expected initializer before '*' token
main.cpp: In function 'int main()':
main.cpp:27: error: 'open' was not declared in this scope
In file included from ISBNPrefix.cpp:11:
ISBNPrefix.h:14: error: expected initializer before '*' token

The compile error in main() is because open() is not declared. It should be declared in my .cpp file, but I can't get it to recognize that it needs to return a FILE..... variable? Type? whatever, naming conventions are the least of my concerns right now

[Moe45673]

Morning bump! My assignment's due by Wed morning and I'm still stuck!

[Zhuge]

Could you show ISBNPrefix.h?

[Moe45673]

No prob!

Here's the main code:

http://pastebin.com/ZmFAikFR (ignore that red text I commented out)

Here's the ISBNPrefix.h (as you can see, both the main code and the definition file include it):
http://pastebin.com/GLu0zY5z

Here's the ISBNPrefix.cpp (all I've done, so far):

http://pastebin.com/FG31A6Cb

[hanst99]

Little side question - why the hell are you using FILEs when the course is supposed to teach you C++? Makes no sense.

[Zhuge]

You are missing a semicolon after the closing } for your struct.
EDIT: In the header, of course.

[Moe45673]

hans, The instructions specify to use it. It's trying to transition us from C to C++ and we're still in the early stages. The focus of the assignment is on modules and teaching the proper syntax for using FILEs in C++ (fstream and the like) is beyond the scope of this assignment

Zhuge: Forehead slap. I'll do that and see what occurs

EDIT

It worked! You're a genius! Full marks! I name today Zhuge Month!