error LNK2001: unresolved external symbol - C / C++ / MFC Discussion Boards

Re: Arrays

David Crow24-Mar-09 2:41

David Crow

24-Mar-09 2:41

Neal beavis wrote:
...i still dont understand wot printf("\n%d", is used for?

Did you consult the MSDN page that was mentioned? It says right there in black & white what printf() does.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

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Re: Arrays

CPallini24-Mar-09 1:43

CPallini

24-Mar-09 1:43

Anyway there's a flaw, it should be:

int i = 10 + rand() % (21 - 10);

to generate a number ranging from 10 to 20 (including bounds).
In the above example you may also be correct (because you didn't mentionate of including both of the bounds), but in your original post, (19-0) is wrong, because rand() % (19-0) ranges from 0 to 18 (bounds included).
-- Carlo the Nitpick.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: Arrays

Eytukan24-Mar-09 1:53

Eytukan

24-Mar-09 1:53

Silent. Let him use it. This is not a bug. Because it won't crash his program nor he will ever come to know it. It looses both the qualification of being a bug. So Jig | [Dance]

it cannot be booked. $Shucks | :-\$ lol, let me change it Smile | :)

He never answers anyone who replies to him. I've taken to calling him a retard, which is not fair to retards everywhere.-Christian Graus

Re: Arrays

CPallini24-Mar-09 3:22

CPallini

24-Mar-09 3:22

ODBC database problem

Deepu Antony24-Mar-09 0:55

Deepu Antony

24-Mar-09 0:55

Hi all

I am using a database application program using ODBC with MS Access as the database.
While navigating through the database,it is missing a particular row.

my code look like this

m_rs.Open( CRecordset::snapshot, _T( "SELECT * FROM DAUArinc717Frame2" ) );
m_rs.Move( Index );
for(i=0;i<128;i++)
{

data = (BYTE)strtoul( m_edit2, 0, 16 );
str.Format("%d",data);

m_rs.Edit();
m_rs.m_Data = str;
m_rs.Update();
m_rs.MoveNext();

b2 = strtoul( m_edit2, 0, 16 )>> 8;
str.Format("%d",b2);
m_rs.Edit();
m_rs.m_Data = str;
m_rs.Update();
m_rs.MoveNext();

}

I am updating to the database, the values read from the GUI.In this process when i==3,in that particular location in my database(row==264),it is skipping without updating and is moving to the next row.

Please help me..

Thanks in advance

Regards
Deepu

Re: ODBC database problem

David Crow24-Mar-09 2:48

David Crow

24-Mar-09 2:48

Deepu Antony wrote:
In this process when i==3,in that particular location in my database(row==264),it is skipping without updating and is moving to the next row.

So does Update() throw an (CDBException) exception?

Re: ODBC database problem

Deepu Antony24-Mar-09 3:23

Deepu Antony

24-Mar-09 3:23

Thanks for the reply.
it is working now.I didn't changed anything.Sometimes it happens like that.
Don't know the exact reason

error LNK2001: unresolved external symbol

ytubis24-Mar-09 0:26

ytubis

24-Mar-09 0:26

Hi!
I need help with this problem, I got this error before but I managed to solve.
But now I have a case with the virtual function.
The source looks like this(after the code I continued writing):

#include "stdafx.h"
#ifndef EMPTRANSH
#define EMPTRANSH
#include "Global.h"
#include "iostream"
#include "string"
using namespace std;

class EmpTrans
{
private:
int id;
char emp_name[MAXNAMELENGTH];
employee_status emp_st;
int salary;
salary_type sal_st;
char deal_date[DATELENGTH];
public:
EmpTrans();
static void Open();
static void Close();
void ReadNext();
virtual void Apply();

void UpdateId(int i){id = i;}
void UpdateSalary(int s){salary = s;}
void UpdateEmployeeStatus(employee_status es){emp_st = es;}
void UpdateSalaryType(salary_type ss){sal_st = ss;}
void UpdateDate(char * d){strcpy(deal_date,d);}
void UpdateEmployeeName(char en){emp_name[0] = en;}
int GetId(){return id;}
char * GetEmployeeName(){return emp_name;}
employee_status GetEmployeeStatus(){return emp_st;}
int GetSalary(){return salary;}
salary_type GetSalaryType(){return sal_st;}
char * GetDate(){return deal_date;}
};
#endif

class EmpTransAdd : public EmpTrans
{
public:
void Apply();
};

class EmpTransChange : public EmpTrans
{
public:
void Apply();
};

class EmpTransDelete : public EmpTrans
{
public:
void Apply();
};

When I compile and link this source I get the error,
when I remove the virtaul function from the Apply function, everything works fine.
What is the problem?
Do I need to take out the other classes from the source? or to include them inside the ifdef?

Thanks Smile | :)

Re: error LNK2001: unresolved external symbol

Cedric Moonen24-Mar-09 0:35

Cedric Moonen

24-Mar-09 0:35

You don't provide a body for the EmpTrans::Open(), EmpTrans::Close(), EmpTrans::Apply functions (well at least you didn't show us). You still need to provide a body for those functions in the base class, unless they are pure virtual functions (e.g. virtual void Apply() = 0;), in which case it is mandatory that each child classes implement this function.

Cédric Moonen
Software developer

Charting control [v1.5]
OpenGL game tutorial in C++

Re: error LNK2001: unresolved external symbol [modified]

S p k 52124-Mar-09 0:37

S p k 521

24-Mar-09 0:37

Will u pls show the code which creates the instance of ur class EmpTrans?
you have to provide the definition of Apply() in the base class. else it have to be a pure virtual function.

modified on Tuesday, March 24, 2009 6:44 AM

Re: error LNK2001: unresolved external symbol

Eytukan24-Mar-09 0:40

Eytukan

24-Mar-09 0:40

if you do not have implementation for virtual void Apply() in class EmpTrans, you should make it.

virtual void Apply()=0

A pure virtual function,

He never answers anyone who replies to him. I've taken to calling him a retard, which is not fair to retards everywhere.-Christian Graus

string append with \ symbol

Thilek23-Mar-09 23:23

Thilek

23-Mar-09 23:23

hi guys,

i am developing a worm scanner..
i have to choose the directories from Folder Browser Dialog..
when i does that i will get the directory C:\NVIDIA\Win2KXP
but i need to convert it to C:\\NVIDIA\\Win2KXP so that i can get the file names in the that directory using ListFiles......

since the symbol \ i could not put \ between "" and ''

how can i solve this ya??

help me plz...

Re: string append with \ symbol

Eytukan23-Mar-09 23:33

Eytukan

23-Mar-09 23:33

Thilek wrote:
but i need to convert it to C:\\NVIDIA\\Win2KXP so that i can get the file names in the that directory using ListFiles......

You don't need to convert it. You can use them straight. Only when you hard-code, you'll have to do this. Your question is slightly blurred to me though.

He never answers anyone who replies to him. I've taken to calling him a retard, which is not fair to retards everywhere.-Christian Graus

Re: string append with \ symbol

Thilek23-Mar-09 23:40

Thilek

23-Mar-09 23:40

when i use C:\Private_Folder\forGetz its not seaching or getting the file name.. unless i use C:\\Private_Folder\\forGetz or C://Private_Folder//forGetz then its working Frown | :(

but when i use folder browser dialog , i will be getting as C:\Private_Folder\forGetz....

Re: string append with \ symbol

Maxwell Chen23-Mar-09 23:51

Maxwell Chen

23-Mar-09 23:51

Are you using std::string to hold the value?

Maxwell Chen

Re: string append with \ symbol

Thilek23-Mar-09 23:58

Thilek

23-Mar-09 23:58

yes....

Re: string append with \ symbol

David Crow24-Mar-09 2:51

David Crow

24-Mar-09 2:51

Thilek wrote:
when i use C:\Private_Folder\forGetz its not seaching or getting the file name.. unless i use C:\\Private_Folder\\forGetz or C://Private_Folder//forGetz then its working

Because those are string literals, which must contain double backslahes.

Thilek wrote:
but when i use folder browser dialog , i will be getting as C:\Private_Folder\forGetz....

Which is correct.

Re: string append with \ symbol

KarstenK24-Mar-09 0:03

KarstenK

24-Mar-09 0:03

You must understand the difference between the hardcoded "\\" and thr "\" in the value of the variable. D'Oh! | :doh:

"\\": is an so calles 'escape sequence' FOR representing the "\" in the string. Look in the values of strings int the debugger Blush | :O

Press F1 for help or google it.
Greetings from Germany

Re: string append with \ symbol

Thilek24-Mar-09 0:34

Thilek

24-Mar-09 0:34

thanks ya...

Re: string append with \ symbol

Thilek24-Mar-09 3:14

Thilek

24-Mar-09 3:14

its so funny that i been breaking my head for days with this... thanks a lot.. u saved me...

Writing a callback function?

Maxwell Chen23-Mar-09 22:56

Maxwell Chen

23-Mar-09 22:56

I am trying to write a simple callback function for my own purpose, not to pass into Windows API as callback arguments. What I did below gets access violation. Where did I do wrong in the below code? Thanks.

typedef void (*fC)(int* p);

bool Test(int n, fC* p)
{
	int* pN = new int;
	*pN = 3;
	(*p)(pN);    // ---- access violation 0xc0000005.
	delete pN;

	return true;
}

void fc(int* p)
{
	*p;
}


void main()
{
	Test(3, (fC*)&fc);
}