Thread: Help with simple console to dll code

I hope someone can help. I’m new to Visual C++ 2008 and I just need help converting a program I wrote to a dll. Here's the program...

Code:

#include "stdafx.h"
#include <stdio.h>			
#include <tchar.h>
#include <iostream>			
#include <valarray>
			
using namespace std;


int _tmain(int argc, _TCHAR* argv[])
{
// Define Variables
	char invalue[850] = "";
	char outvalue[] = "";
	unsigned int v=0;
	unsigned int vlen=0;
	

// Get in value		
	cin >> invalue;


// Setup Values of Variables 
	vlen = strlen(invalue);
	outvalue[0] = invalue[0];
	
// Loop
    for(v;v<vlen-1;v++)
    {						
	outvalue [0] ^=  invalue[v+1];   
	
    }

// Prints results
	printf ("%x \n", outvalue[0]); 

  
  return 0;

Basically it takes a sting like "AS0100012178 2178" and XOR's each character then takes the result and displays the hex value of the result (in this case should be 1e). In the dll though, i'll need it to output the hex value to the program i'm using. I've tried for two weeks and can't seem to figure out how a dll works completely.

Anyone think they can help me?! It would be greatly appreciated as I’m pulling my hair out!

Thanks!

I've tried but I don't understand how to export the results to an external program. That and from what little I understand you need to return the info I need thru the return command, not the print command right?

So in that case does anyone know how to assign the 2 digit hex value of a character to a variable?

Anyone still know how to return a HEX value then?

Any examples? Sorry to be suck a pain!

What, an example of how to return an integer?

Code:

int sample() {
    return (0x1e);
}

The result you have is technically a char (outvalue[0]), so you can return a char and printf it with %x in your other program the same way.

The other program I am using I'm not acually writing, so it can't convert, say the char of "N" to a hex value of "4e". So i'll need the dll to do that. The main trouble I having still is I still don't know how to setup the export correctly. The program i'm using asks for just the location of the dll, function name to call, function parameters and then where to send the results.

I've named my project ecc and create an export.def with the following...

Code:

LIBRARY ecc
EXPORTS
     ecc

but I don't know how to recieve the string in correctly...

Code:

__declspec(dllexport)char invalue[850]

My Hat of Guessing thinks you mean

Code:

__declspec(dllexport)char ecc(char invalue[850]) {
// function goes here
}

but isn't entirely sure if this is what you're asking. You are exporting a function named ecc? (I've never used declspec et al, so I have no idea, but I'm pretty sure you need to be exporting some kind of function, and why not let that function take a parameter?)

Originally Posted by crazybucky

Any examples? Sorry to be suck a pain!

The DLL

Code:

// myDLL.cpp
// Compile: cl.exe /LD myDLL.cpp

#include <string.h>

#define DECLARE_EXPORT __declspec(dllexport)

extern "C"
{
    DECLARE_EXPORT void myFunction( char* pIn, unsigned char * pOut )
    {
	int v, vlen;	
	
	vlen = strlen(pIn);
	   for(v = 0; v < vlen; v++)
	pOut[v] =  pIn[v] + 1;   
    }
}

The calling code

Code:

// Example of explicit linking of DLL
#include <windows.h>
#include <stdio.h>

// Function pointer
typedef void (*myFunction)(char *, unsigned char *);

int main(void)
{
	myFunction _myFunction;
	char cInput[] = {"AS0100012178 2178"};
	unsigned char ucReturn[24] = {0};
	int iIndex;
	HINSTANCE hInstLibrary = LoadLibrary("myDLL.dll");

	if (hInstLibrary)
	{
		_myFunction = (myFunction)GetProcAddress(hInstLibrary, "myFunction");
		if (_myFunction)
		{
			 _myFunction(cInput, ucReturn);
			for(iIndex = 0; iIndex < strlen(cInput); iIndex++)
				printf("%c         %c  0x%02X\n", cInput[iIndex], ucReturn[iIndex],ucReturn[iIndex]);
		}
		else printf("_myFunction failed to initialize\n");
		FreeLibrary(hInstLibrary);
	}
	else printf("myDLL.dll failed To Load!\n");
	return 0;
}