string and dll

**madzombie** · 12-11-2008

my dll function is ;

Code:

char* _stdcall pages(char* pageID){
	char *p = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\">\n<HTML><HEAD>\n<META http-equiv=Content-Type content=\"text/html; charset=windows-1252\">\n</HEAD>\n<BODY><p>";
if (pageID == 'm') {
	char* p2 = "madzombie deneme";
} else {
char* p2 = "deneme";
}
	char* p3 = "\n<p>\n</BODY></HTML>\n";
	int l1 = StringLength(p);
	int l2=StringLength(p2);
	int l3=StringLength(p3);
	int toplam = l1+l2+l3;
	char* sonuc = new char[toplam];
	strcpy(sonuc,p);
	strcat(sonuc,p2);
	strcat(sonuc,p3);
	
	return sonuc;
}

But the function give an error and my project time-out.
char p1 and char p3 are static variable. char p2 is dynamic variable.
what can i do ?

**madzombie** · 12-11-2008

and StringLength function;

Code:

int StringLength(char inputString[])
{
    int length = 0;
    for (int i = 0; inputString[i]!= '\0'; i++)
        length++;
    return length;
}

**madzombie** · 12-11-2008

i write on Dev-cpp and this codes runnig. But it isn't running on VS 2008 win32 dll project.

Code:

#include <cstdlib>
#include <iostream>
#include <windows.h>
using namespace std;
char* _stdcall denem();
int StringLength(char inputString[]);
int main(int argc, char *argv[])
{

   cout << denem();
    system("PAUSE");
    return EXIT_SUCCESS;
}
char* _stdcall  denem(){
   char *p = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\">\n<HTML><HEAD>\n<META http-equiv=Content-Type content=\"text/html; charset=windows-1252\">\n</HEAD>\n<BODY><p>";
	char* p2 = "madzombie deneme";
	char* p3 = "\n<p>\n</BODY></HTML>\n";
	int l1 = StringLength(p);
	int l2=StringLength(p2);
	int l3=StringLength(p3);
	int toplam = l1+l2+l3;
	char* sonuc = new char[toplam];
	strcpy(sonuc,p);
	strcat(sonuc,p2);
	strcat(sonuc,p3);

    return sonuc;
}
int StringLength(char inputString[])
{
    int length = 0;
    for (int i = 0; inputString[i]!= '\0'; i++)
        length++;
    return length;
}

**rags_to_riches** · 12-11-2008

What do you mean by "isn't running"? Does it not build? One thing to note is that a DLL doesn't usually have a standard main entry point. And _stdcall is __stdcall (you need another _).

**madzombie** · 12-11-2008

the project
http://www.ulutascomputer.com/main.rar

**Codeplug** · 12-11-2008

You need to add 1 to toplam to make room for the null-terminator.

p, p2, and p3 should be const.

If you're willing to use strcpy and strcat, then use strlen as well.

Your DLL needs to have a FreeString() function so that the memory returned denem() can be deleted.

gg

**rags_to_riches** · 12-11-2008

The DLL built fine for me once I added the project to a solution in VS 2008. But you've still not told us what exactly the problem is, so that's the best I can tell you. And don't forget codeplug's feedback.

**madzombie** · 12-11-2008

My Win32 dll function ;

Code:

char* _stdcall pages(){
	const char* p ="deneme 1";
	const char* p2 = "deneme 2";
	int p_len = strlen(p);
	int p2_len = strlen(p2);
	int toplam = p_len + p2_len + 1;
	char* yeni = new char[toplam];
	strcpy(yeni,p);
	strcat(yeni,p2);
	return yeni;
}

My C# Project;

Code:

     [DllImport("dlldeneme.dll")]
        public static extern string pages();

Code:

     private void button1_Click(object sender, EventArgs e)
        {
            string cevap = pages();
            listBox1.Items.Add(cevap);
        }

Error Message;

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

**Codeplug** · 12-11-2008

I'm no C# guru - but you probably need a marshaling attribute like "[MarshalAs(UnmanagedType.LPTStr)] String".

http://msdn.microsoft.com/en-us/library/s9ts558h.aspx

gg

string and dll

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