CFile---reda write - C / C++ / MFC Discussion Boards

mekanoo23-Jun-05 22:33

23-Jun-05 22:33

....ha ! what a buggy thing..!
did you think about bitwise extraction ?
single and double are stored in a defined as'IEEE_754' standard:
1.Bit = +/-
2.-9. is Exponent
10.-32. is Mantisse
but all is counted from right to left &
starting with 0. to 31......so
have look at these definitions and get your numbers as bits from there

Typ Gesamtgröße Mantisse Exponent Bias
single 32 bit 23 bit 8 bit 127
double 64 bit 52 bit 11 bit 1023
Smile | :)

http://www.computerbase.de/lexikon/IEEE_754

Re: conversion confusion...

mekanoo23-Jun-05 22:53

mekanoo

23-Jun-05 22:53

...a little grammar confusion in my last reply....

i want to add:
i had to deal with the extraction of 'float'= single and 'real'= double data
from a stream.
so i looked for bit-manipulation code thats around..because it's not really easy.
1. the exponent is stored with added value to avoid negative numbers...
2. the whole number is a expression from 2^xyz ....
&&&

--------------
if that doesn't help you really then it gives you at least ahint for the reason of that conversion phanomena.
-------------
.Net Framework helped me out there wit the BitConverter Class.... Suspicious | :suss:

Re: conversion confusion...

GDavy23-Jun-05 23:21

GDavy

23-Jun-05 23:21

Thanks for the reply..
I looked up the IEEE standard you mentioned for floating point arithmetic.. Nice documentation, thanks. It's indeed explaining the peculiar behaviour I noticed.
Been so long since I looked at a basic C-type at such a low level that it was a nice refreshment!
Rose | [Rose]

Re: conversion confusion...

mekanoo24-Jun-05 0:13

mekanoo

24-Jun-05 0:13

Re: conversion confusion...

Gary R. Wheeler24-Jun-05 3:25

Gary R. Wheeler

24-Jun-05 3:25

void AFunction(double dNumber,int acc)
{
  int nDecimal = (int)dNumber;
  double dFract = dNumber - (double)nDecimal;
  double dFactor = 1.0;
  for (int dFi = 0; dFi < acc; dFi++) dFactor *= 10.0;
  int nFract = (int)((dFract * dFactor) + 0.5);
}

Hmm. I made the scale factor a double, and calculated it with a simple loop (the fastest solution would be to use an array lookup). I also rounded the result.

Software Zen: delete this;

Re: conversion confusion...

mekanoo25-Jun-05 2:32

mekanoo

25-Jun-05 2:32

......the ") + 0.5)" is a integer conversion tactic i saw at vb-accelerator.com
as well...>>>that must do!!
it ensures the rounding up to the next number bcause the int-conversion just kills the fraction after the '.' - Ha!

Working with Media Files

Adeel68823-Jun-05 20:51

Adeel688

23-Jun-05 20:51

In MFC is there any way to Detect the currently playing song (mp3, mp4, wma, ra, wav, ogg, aac, aif)in a user's media player (iTunes, Windows Media Player, Winamp, Real, Napster etc.)
Cry | :((

:->

CFile---reda write

a_du23-Jun-05 20:02

a_du

23-Jun-05 20:02

Hey,
i want to read and write a .csv file using CFile. the records are like the following:
1.tif,Transferred,12:00-12:10,10KB/S
2.tif,Transferred,12:30-12:40,10KB/S
3.tif,Transferred,13:00-13:10,10KB/S

how can i load the contents into a CString and how can i read content line by line into a CString by using CFile class?
CFile::GetLength resturns the length of the file. but, if i define a buffer[length] to load the data, i found that the last few chars of the array are mass things.How does this come?
Thanks a lot! Sniff | :^)

Re: CFile---reda write

ThatsAlok23-Jun-05 21:14

ThatsAlok

23-Jun-05 21:14

a_du wrote:
want to read and write a .csv file using CFile.

Instead of CFile use it's derived Class CStdioFile,as it's Member Function CStdioFile::ReadString read file LINE by LINE

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta

Re: CFile---reda write

Priyank Bolia23-Jun-05 21:29

Priyank Bolia

23-Jun-05 21:29

I guess you should use CStdioFile instead of CFile and use function like ReadString and WriteString. Then use Tokenize function of CString to parse the data.
a_du wrote:
if i define a buffer[length] to load the data, i found that the last few chars of the array are mass things.How does this come

<br />
byte buffer[length + 1];<br />
buffer[length] = '\0';

http://www.priyank.in/

COMPARE 2 Strings

ana_bahy23-Jun-05 20:02

ana_bahy

23-Jun-05 20:02

Hey , i got a small tiny littile Question...
which is:

string string1;
string string2;

i wana check if da first 10 char in string1 == da first 10 char in string 2
how can i write that in c++??

Sorry for bothering ,
My regards,
Bahy

Re: COMPARE 2 Strings

Maxwell Chen23-Jun-05 20:32

Maxwell Chen

23-Jun-05 20:32

using std::string;<br />
<br />
int main()<br />
{<br />
	string a("1234567890INTEL");<br />
	string b("1234567890AMD");<br />
<br />
	if(10 > a.length() || 10 > b.length()) {<br />
		std::cout << "Length.\n";<br />
		return 0;<br />
	}<br />
<br />
	std::cout << a.c_str() << "\n";<br />
	std::cout << b.c_str() << "\n";<br />
<br />
	int res = a.compare(0, 10, b, 0, 10);<br />
	std::cout << "res = " << res << ".\n";<br />
<br />
	return 0;<br />
}<br />

Maxwell Chen

Re: COMPARE 2 Strings

Weiye Chen23-Jun-05 20:36

Weiye Chen

23-Jun-05 20:36

One way would be to copy out the 10 characters in each string before comparing

char szStr1[11], szStr2[11];
 
// Copy first 10 characters
strncpy(szStr1, string1, 10);
strncpy(szStr2, string2, 10);
 
// Append null terminating character
szStr1[10] = '\0';
szStr2[10] = '\0';
 
// Start comparing
if(strcmp(szStr1, szStr2) == 0)
{
   // They are equal
}

<font=arial>Weiye Chen
Life is hard, yet we are made of flesh...

Re: COMPARE 2 Strings

ana_bahy23-Jun-05 20:42

ana_bahy

23-Jun-05 20:42

thanks u soo much ..bt it gave me an error at those lines
strncpy(szStr1, string1, 10);
strncpy(szStr2, string2, 10);
and the error is
cannot convert parameter 2 from 'class std::basic_string<char,struct std::char_traits<char="">,class std::allocator<char> >' to 'const char *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

SO what can i do??
My regards..
bahy

Re: COMPARE 2 Strings

toxcct23-Jun-05 20:49

toxcct

23-Jun-05 20:49

replace string1 with string1.c_str()

cheers,

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: COMPARE 2 Strings

ana_bahy23-Jun-05 20:58

ana_bahy

23-Jun-05 20:58

Thank You soooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo Much...

Re: COMPARE 2 Strings

toxcct23-Jun-05 21:00

toxcct

23-Jun-05 21:00

wow, no problem Smile | :)

it was a pleasure !

Cool | :cool:

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: COMPARE 2 Strings

ana_bahy23-Jun-05 21:14

ana_bahy

23-Jun-05 21:14

Hello My Teacher ,
Can i ask you 1 more question , (if u dont mind)
How can i ask the user to insert a string , and to be saved in Title
i believe if it was a char[30] i can use

char Title[30];
cin.getline(Title,30);

But what is the case if it String??

My regards,
Bahy

Re: COMPARE 2 Strings

Maxwell Chen23-Jun-05 21:14

Maxwell Chen

23-Jun-05 21:14

I thought ana was asking the C++ string type.... D'Oh! | :doh:

Maxwell Chen

Re: COMPARE 2 Strings

GDavy23-Jun-05 21:15

GDavy

23-Jun-05 21:15

or in just 1 line:
strncmp( string1.c_str(), string2.c_str(), 10);

Re: COMPARE 2 Strings

ana_bahy23-Jun-05 21:25

ana_bahy

23-Jun-05 21:25

Hey ,,thanks for da code , it really works fine...
but can u tell me what does it mean , cause i cant understand how it works..
My regards,
ana bahy

Entry and exit (When Exit its does entry)

Cillieacc0rd5o423-Jun-05 19:46

Cillieacc0rd5o4

23-Jun-05 19:46

Hi i am using this code to Initialize a driver when the DLL is used.
I want it initialzse the driver when the DLL is used.
And when the DLL is exited or is not used no more the driver unloaded.
The problem i am having is, That whne it loads its fine, but when i unload the DLL. It loads the driver twice and then it displays unload. Can i somehow fix the double load and then load problem somehow?

void exitfkt(void)
{
MessageBox(NULL,"Unload Dll", "Test", MB_ICONINFORMATION | MB_OK);
}

BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
MessageBox(NULL,"Load Dll", "Test", MB_ICONINFORMATION | MB_OK);
atexit(exitfkt);

return TRUE;
}

Re: Entry and exit (When Exit its does entry)

ThatsAlok23-Jun-05 22:52

ThatsAlok

23-Jun-05 22:52

Cillieacc0rd5o4 wrote:
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
MessageBox(NULL,"Load Dll", "Test", MB_ICONINFORMATION | MB_OK);
atexit(exitfkt);

return TRUE;
}

change it to..........

BOOL APIENTRY DllMain( HANDLE hModule, 
DWORD ul_reason_for_call, 
LPVOID lpReserved
)
{

switch(ul_reason_for_Call)
{
case <code>DLL_PROCESS_ATTACH</code>:
MessageBox(NULL,"Load Dll", "Test", MB_ICONINFORMATION | MB_OK);
break;
case <code>DLL_PROCESS_DETACH</code>:
atexit(exitfkt);
break;
}
return TRUE;
}

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta

is this a memory leak?

Hums23-Jun-05 19:02

Hums

23-Jun-05 19:02

say you have a base class

class base
{
public:
[vars]
[funcs]
virtual void func()=0;
};

and child class that inherits the base but adds some of its own variables and functions

class child: public base
{
public:
[more vars]
[more funcs]
void func() {[statements]};
};

if you then were to declare, use, and release as follows, is there a memory leak, or other problem? It seems wrong to me, but I want to do it this way.

base* apple;

apple = new child;

apple->func();

delete apple;

Thanks for any help.

Re: is this a memory leak?

Weiye Chen23-Jun-05 19:20

Weiye Chen

23-Jun-05 19:20

There's nothing wrong i believe. Just make sure your child class has a virtual destructor to clean up whatever memory allocations you made in it.

<font=arial>Weiye Chen
Life is hard, yet we are made of flesh...

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