C / C++ / MFC Discussion Boards

Re: Complex Equations...

Anonymous9-Feb-03 11:39

Anonymous

9-Feb-03 11:39

How would I get the 'r' and 'i' values from the 'z'???

Re: Complex Equations...

EnigmaticalShadow9-Feb-03 16:14

EnigmaticalShadow

9-Feb-03 16:14

How would I get the Real and Imaginary values from the 'z'???

Re: Complex Equations...

Steve Mayfield9-Feb-03 18:52

Steve Mayfield

9-Feb-03 18:52

double real, imag;
complex cplx;
T = complex(1.0, 2.0)
real = cplx.real();   /* returns the real part of cplx */
imag = cplx.imag();   /* returns the imaginary part of cplx */

Re: Complex Equations...

9-Feb-03 20:15

It gives me an error saying 'complex' is "undeclared identifier"...
What I need to do after I got 'z' is this:

Final = abs(pow(pow(z[REAL PART], 2) + pow(z[IMAGINARY PART], 2), 0.5));

'double Final' is a single value...

Thanks...

Re: Complex Equations...

markkuk10-Feb-03 2:03

markkuk

10-Feb-03 2:03

#include <complex>
using namespace std;
double final;
complex<double> z(1.0, 2.0);

// final = abs(sqrt(pow(z.real(), 2) + pow(z.imag(), 2)));
final = abs(z);

pow(x, 0.5) is the same as sqrt(x).
abs(z) where z is a complex number calculates the same value as your formula.

Re: Complex Equations...

EnigmaticalShadow10-Feb-03 6:45

EnigmaticalShadow

10-Feb-03 6:45

When I do the calculations this way:

z = (2, 3);
c = (-4, -5);
z = std::pow(z, 2) + c;
Final = abs(sqrt(pow(z.real(), 2) + pow(z.imag(), 2)));

I get a different answer than this:

r2 = 2; i2 = 3;
r = -4; i = -5;
r3 = (r2 * r2) + (-(i2 * i2));
i3 = (i2 * r2) + (i2 * r2);
r5 = r3 + r;
i5 = i3 + i;
r2 = r5;
i2 = i5;
Final = abs(pow(pow(r5, 2) + pow(i5, 2), 0.5));

The second way seems to give me the correct answer... Thanks...

Re: Complex Equations...

EnigmaticalShadow10-Feb-03 7:16

EnigmaticalShadow

10-Feb-03 7:16

Nevermind, I figured it out... I had "complex<double> z = (2, 3);" instead of "complex<double> z(2, 3);"...

Dialog Box Question

Paddy9-Feb-03 8:58

Paddy

9-Feb-03 8:58

When a modal dialog box is closed using EndDialog does it's parent window recieve a message to notify it that the dialog has closed? I want to update some info in my status bar as soon as the dialog is closed.

Thanks in advance,
Paddy

Re: Dialog Box Question

Nish Nishant9-Feb-03 9:05

Nish Nishant

9-Feb-03 9:05

If this is MFC, then DoModal returns only when EndDialog is called. If this is a non-MFC modal dialog you created by calling DialogBox, then DialogBox won't return till EndDialog is called.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Dialog Box Question

Paddy9-Feb-03 9:55

Paddy

9-Feb-03 9:55

Thanks for the help. It's non-MFC I'm using. Does this mean that my main window can't do anything until EndDialog is called?

Paddy

Re: Dialog Box Question

Nish Nishant9-Feb-03 12:21

Nish Nishant

9-Feb-03 12:21

Paddy wrote:
It's non-MFC I'm using. Does this mean that my main window can't do anything until EndDialog is called?

Yup, your main window will be frozen. An alternative is to use a modeless dialog, or use threads.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

crash with push_back for vector

nss9-Feb-03 7:58

nss

9-Feb-03 7:58

What am I doing wrong? I want to read the names from a file and put them onto a vector of char*......it crashes at the pushback. Each file name is on a different line.

I did a dir/b in dos and got a txt file with a list of file names (a bunch of .bmps) from the directory. I assume theres carriage returns at the end of each line. But maybe not. There are 18 letters in the name08FEB096_9571s.bmp, and carriage return line feed is 1 byte (MSDN).

CFile file;

std::vector<char*> fileVec;

file.Open("c:\\miss\\SImages.txt", CFile::modeRead, 0);

char* pBuf;

char folder[200];

strcpy(folder , "C:\\miss\\");

for (int i = 0; i <96; i++)
{

    pBuf = new char[200];

    file.Read( pBuf,20);

    strcat(folder, pBuf);

    fileVec.push_back(folder);

    delete[] pBuf;
}


file.Close();

Re: crash with push_back for vector

C^hris L^osinger9-Feb-03 8:50

C^hris L^osinger

9-Feb-03 8:50

looks like the board ate some of your code. how is your vector defined? (what is it a vector of?)

-c

WWT2D?

Fractals

Re: crash with push_back for vector

nss9-Feb-03 13:11

nss

9-Feb-03 13:11

It was avector of CString. However my problem was that I was using CFile when CStdioFile was more suitable and I had overwritten some buffers, but the poor vector got blamed....

Thanks. Smile | :)

Re: crash with push_back for vector

Solomon Wu9-Feb-03 18:17

Solomon Wu

9-Feb-03 18:17

CFile file;
change std::vector fileVec;
to std::vector<string> fileVec;

Move strcpy(folder,"c:\\miss\\");
to For Statement

for (int i = 0; i <96; i++)	{		
    strcpy(folder , "C:\\miss\\");	
    pBuf = new char[200];			
    file.Read( pBuf,20);		
    strcat(folder, pBuf);		
    fileVec.push_back(folder);		
    delete[] pBuf;	
}

Learning and Working

Re: crash with push_back for vector

Jambolo9-Feb-03 21:55

Jambolo

9-Feb-03 21:55

Nobody explained the reason for the crash...Without the unimportant stuff, here is what the code looks like. Do you see the problem?

char folder[200];
strcpy(folder , "C:\\miss\\");
for (int i = 0; i <96; i++)
{
...
strcat(folder, pBuf);
...
}

thanks everyone!!!

ns10-Feb-03 1:15

10-Feb-03 1:15

Yup. I saw finally....my poor "folder" variable was getting concatenated way beyond its allocated space...
Thanks

Appreciate your help,
ns

reading a string from a file with CFile Read()

nss9-Feb-03 6:40

nss

9-Feb-03 6:40

I have a file with several lines of text (all end with a carriage return). I want to use my CFile object to read these strings into an array of pointers to char. I dont see a anything like GetLine()....if I dont know the length of the text on the line, I dont have a value to give Read() as a count of chracters...
Actually I'm push_backing the strings onto a vector...

Re: reading a string from a file with CFile Read()

C^hris L^osinger9-Feb-03 7:12

C^hris L^osinger

9-Feb-03 7:12

try CStdioFile

-c

WWT2D?

Fractals

Thank you!!!!!

nss9-Feb-03 8:19

nss

9-Feb-03 8:19

That is working out......many thanks.

Calling functions in DLL

hongheo769-Feb-03 5:24

hongheo76

9-Feb-03 5:24

Hi,

I got a DLL (not MFC) with some functions in it. The header file containing the declaration for the functions of the DLL is also available.

Is there a way to call these functions in a static way other than using LoadLibrary and GetProcAddress ?

Thanks

Re: Calling functions in DLL

Roman Nurik9-Feb-03 5:29

Roman Nurik

9-Feb-03 5:29

yes, include the header file:

#include "MyDllBase.h"

and link the project with the output .LIB file for the DLL

under project settings->linker->input, add "MyDllBase.lib"

- Roman -

SIMPLE db example

JockeP9-Feb-03 4:58

JockeP

9-Feb-03 4:58

Hi!

I have tried to find a simple way to manipulate a database (in MS Access or MS SQL Server). However, I've not succeeded. I've tried SELECT statements with CRecordset and it works. But it seems like only SELECT statements work. This is what I've tried:

CDaoDatabase* m_pDB;
CDaoRecordset* m_pRS;
m_pDB = new CDaoDatabase;
m_pRS = new CDaoRecordset(m_pDB);

try {
m_pDB->Open("c:\\accessdb\\db1.mdb");
// CString strQuery = _T("SELECT * FROM Table1"); //Works just fine...
CString strQuery = _T("INSERT INTO Table1 VALUES ('3', 'Olga')"); //Doesn't work
m_pRS->Open(dbOpenDynaset, strQuery);
} catch (CDaoException* e) {
AfxMessageBox(e->m_pErrorInfo->m_strDescription);
e->Delete();
}

So how do you add data to a table, modify tables and so on?

Cheers,
Joachim

Re: SIMPLE db example

l a u r e n9-Feb-03 7:15

l a u r e n

9-Feb-03 7:15

im assuming the 3 in ur insert statement goes into a numeric field in the database table ... if so lose the '' around it ... u only have to quote text fields (and prolly date fields sometimes)

"even if my world is weird its my world"
biz stuff about me

Re: SIMPLE db example

Anonymous9-Feb-03 7:17

Anonymous

9-Feb-03 7:17

No, it's a text field

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.