dll to read a file and return the number of lines in the file.

[happiness4all]

following is the code for dll to read a file and return the number of lines in the file.
filedll.cpp

#include "stdafx.h"
#include<iostream>
#include<windows.h>
#include<fstream>
#include<string>
using namespace std;
 
BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved
                     )
{
    return TRUE;
}
 
_declspec(dllexport) int filereader(LPCSTR fpath)
{   int val=0,i=0;
    fstream f;
    string w;
    f.open(fpath,ios::in);
    if(f.is_open())
    {
       while(!f.eof())
       {
           getline(f,w);
           i++;
       }
       val=i;
       f.close();
    }
    else
        val=-1;
 
    return val;
}
 

filedll.def
LIBRARY filedll
EXPORTS
filereader

BUT its not working..it just prints 1..even if the filename passed doesnot exist.

[Silent1Mezzo]

So it looks like its getting into if(f.is_open()) whether the file is open or not. I don't know C++ but is it possible this is returning something other than 1?

[happiness4all]

no its not like dat...
its giving 1 in all da cases..if the file exists and there are many lines in it..

[happiness4all]

but the same code works fine if i run the function from simple program..instead of calling the dll

[weaknessforcats]

Have you tried to follow the path of execution using your debugger??

Other questions:
1) have you loaded the dll??
2) have you used GetProcAddress??

[happiness4all]

yes i have done all that..

[weaknessforcats]

yes i have done all that..

May I see what you have done?

[weaknessforcats]

It just occurred to me:

You are aware that C++ mangles function names???

If you have .cpp file you will nedd to
a) use a DEF file to export the mangled name as a readable one
b) use extern "C" on your C++ function.

With a static lib, the mangled name is used throughout.

Or, you can forget all this and put your code in a .c file. Function names are not mangled in C and a DLL is an old C thingy.

[happiness4all]

I am confused about this mangled name..to be put in def file..

If the following dll works fine without mangled names and extern "C" ..why cant others..

deftry.cpp
#include<iostream>
#include<string>
#include<windows.h>
using namespace std;
 
_declspec(dllexport) int Add(int a,int b)
{
 
    return (a+b);
}
 

deftry.def
LIBRARY deftry
EXPORTS
Add