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Hello,
Is an access to a variable with static modifier faster than a normal variable?
I have a recursive function:
void recursiveSolve(char *pszInput, int nItems)
{
int pArray[10];
}The initial contents of pArray doesn't matter, it gets overwritten in all cases. If I declare pArray as static int[], would the recursive function be faster? I don't know, perhaps a static variable has a fixed position in memory and doesn't get allocated again and again when the function calls itself recursively. Do you know?
-Dominik
_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do?? 
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I think so.
Because a saying said that the more space, the less time.
When stored as static varibles the more space is needed (the none-static varibles will be freed when they won't be needed), so I think the function needs less time to run.
Do you think I am right, don't you?
LeonOrient
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I don't know if that saying applies to this problem
-Dominik
_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??
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It shouldn't matter. It would be better to try and optimise using a better algorithm than changing to static variables
Using static variables is a C concept rather than a C++ concept.
It can be very problematic if you have to port the code into a DLL (look at the MSVC6 STL problems with DLL's for the perfect example)
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i am sorry my friend... static variables is not only a concept in C but it is extensibly used in C++ too. infact "static var" concept is not confined to any language or OS. its a generic concept, which is used in many languages and operating systems. there are some solutions, which are best implemented with static concept.
"Think big, think fast, think ahead. Ideas are no one's monopoly"
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BhaskarBora wrote:
static variables is not only a concept in C but it is extensibly used in C++
Perhaps I worded it badly. But being able to do it doesn't mean you should.
If you have to do something like this why are there so many discussion about the 'meyers singleton' pattern and order of destruction. Dynamic allocation of memory through a static pointer can be walking a dangerous road. Especially if you need to control the order of destruction.
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dear friend ! its up to you how you perceive things !
"Think big, think fast, think ahead. Ideas are no one's monopoly"
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hi there .. u r right partly...
all static variables (no matter where they are defined) are not created on stack like local vars. and also static vars are created once for a process/program and remain till the end. this is the reason when your function has static var array defined rather than a local var array, the execution is faster. as static var is created during the program startup and in your case not everytime when you invoke the function (recursive or otherwise). if it would have been a local array then execution would have been little slower as compare to the static array version (as OS will allocate the array on stack everytime you call the function and removes it from stack when function returns).
static var array is shared in all calls to the function. Also, there is a wastage of memory when you are not using the array. to over come this, you can define a 'int pointer' as static and allocate the memory when you need to use the array. when you no longer want the array, relase the allocated memory. this would be a smart solution !
"Think big, think fast, think ahead. Ideas are no one's monopoly"
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Thanks! I will try the static pointer idea!
-Dominik
_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do?? 
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Now I have been assigned a task to do a FDD test. During the project I don't know how to make the Floppy-Disk-Device's LED blinking. Could you tell me some solutions to it, please.
Thank you!
LeonOrient
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You cannot access the LED of a floppy disk through software!!! It is an integral part of the floppy disk and it has nothing to do with the operating system. Maybe, you could flash the HDD LED (since the BIOS does it) but not that of a floppy.
// Afterall I realized that even my comment lines have bugs
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Oh, Thanks.
Now I have another question, could you help me?
How can I carry out a Sequential-Verify test on floppy disk in VC?
Thank you very much!
LeonOrient
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Sorry but I don't know.
// Afterall I realized that even my comment lines have bugs
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Now I have made FDD's LED blinking as my special ratio
the way is to access some special ports
in addion,
it requires to load a driver
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Hi~
Below source is that find a file on ftp server. (from MSDN example)
By the way, no problem on windows iis ftp server
, but finder.FindFile() always return 1 on unix server .
What's wrong??
CInternetSession sess(_T("MyProgram/1.0"));
CFtpConnection* pConnect = NULL;
pConnect = sess.GetFtpConnection(_T("ftp.microsoft.com"));
CFtpFileFind finder(pConnect);
// start looping
BOOL bWorking = finder.FindFile(_T("*")); // bug !!
while (bWorking)
{
bWorking = finder.FindNextFile();
printf("%s\n", (LPCTSTR) finder.GetFileURL());
}
There are two men, one is a programmer, another is a man.
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I got a ownerdrawn clistctrl that I have a bk image in.
How do I make the selected item background color about 50% transparent (I want to blend it with the bkimage)?
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In the CListCtrl::DrawItem(LPDRAWITEMSTRUCT) function, you can manage the CDC object for fill each item to transparent.
I also need this implementation (with 100% transparent), and if you get please tell me how make it.
[]'s
Cris.
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What the program actually does is that it searches an input file containing special characters contained in some words(i.e Ô , * and #352; ) .After finding such words it replaces those characters with this (i.e \o^ , \e^ and \sh respectively).I hope you will have the picture now.
SPECIFICATION
Deal with input or check whether input has the following special characters, i.e. read a file of text containing a list of words and check for the occurrence of these characters:
Ô or ô * as used in the word "pôô"
* or * - as used in the word "r*ma"
#352; or #353; - as used in the word "le#353;a#353;a"
If a word has any of these character replace each character by the
following characters respectively:
ô with \o^
* with \e^
#353; with \sh
I would appreciate it if you could could have a short program to sort
this issue out.
Let me say that it should be like this:
input -> words.doc
pôô r*ma le#353;a#353;a aôwô b*thô
output -> c:\output.txt
p\o^\o^ r\e^ma le\sh;a\sh;a a\o^w\o^ b\e^th\o^
Yes the text file is ASCII format(that "#352;" represent an S with a cap on top).It is Northern Sotho language(South African language)
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The simple way is to use a lookup table e.g. char lookup[256];
each element will contain the character that is to be displayed for relevent ASCII value e.g lookup[235] = '?'; The majority will probably be the "standard" ASCII values.
So read in a buffer and use the look up table to convert each character, to a new or the same buffer;
This solution is only really valid if there are a lot of mappings that change, otherwise it can be slow. If there are only a few use a simple case statement for the mapped characters.
Of couse you could look at the ASSCII code chart and see if a simple mask would do the job, e.g. converting lower to upper case.
If I have seen further it is by standing on the shoulders of Giants. - Isaac Newton 1676
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Can't think of an application to do this off the top of my head.
However, if what you are looking for is API capable of doing exactly this you could start with:
1/ boost::regex[^]
2/ System.Text.RegularExpressions in the .NET framework
The benefit of using boost::regex is that you get a little more flexibility.
The benefit of using the .NET framework is you can code it in C# and it'll be about 1/4 the size.
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How can i convert _int64 to string? Normally whenever i need to convert numbers to string i use the following code:
**************************************
int num = 123;
std::string strNum;
std::strstream strm;
strm << num << std::ends;
strNum = strm.str();
***************************************
This always works fine for me if the data type of a number is 'int' or 'float'. Today for the first time i need to convert an '_int64' number to string. I am using the code i described above but i get the following error:
ServerMain.cpp(79) : error C2593: 'operator <<' is ambiguous
Can anyone tell me the cause of problem and its solution
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_int64 is a compiler specific data type. Therefor it is not supported by the STL which is by design compiler independant (at least it's supposed to).
You can use the printf() family of functions, they support _int64 via the prefix I64 (but only on MSVC). So this should work:
sprintf(my_char_buffer, "%I64i", my_int64_num);
- askadar
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askadar wrote:
_int64 is a compiler specific data type. Therefor it is not supported by the STL which is by design compiler independant (at least it's supposed to).
However true, it's also irellevant. The STL (which technically has no merit any more, since Mars 1998) didn't even touch the matter.
If we on the other hand talk about the C++ library: vendors are free to extend the library with e.g. compiler specific data types, and both Dinkum (MSVC7 and __int64, though with the name _LONGLONG) and the GNU C++ lib do provide these insertion operators for 64-bit integers (VC6 is another matter, but it's very easy to augment the lib to handle 64-bit integers).
In fact I expect (especially for proprietary) compiler/lib combos to provide operators for all of the compilers POD types. I almost wrote "native types", but stopped myself knowing that any IA32 64-bit integer support must be emulated.
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Hi CPians !
My MFC Dialog app needs to be runned single under NT/XP. To that end I use PJNaughter's single instance which works very fine. I have associated some config files to my app, so that when the user double clicks on them, my app is opened. So far so good.
If my app is already running when the user double clicks on a cfg file, I'd like to send a message from the second instance to the first with the name of the file to open in it, so that i can open the config file in the first, and kill the second.
BUT I can't get this to work.
I use a registered message, which is arriving properly and handled properly with ON_REGISTER_MESSAGE, but I can't retrieve the sent string. :
App2 (which is to be terminated) :
CString Filename="C:\\Myfile.cfg";
::SendMessage(WM_USER_2NDOPEN,(WPARAM)(Filename.operator LPCTSTR()),0);
App1 (which should process the message :
LPCTSTR buff;
buff=(LPCTSTR)wParam;
won't work. I have tried about everything, using LPSTR, LPCSTR, LPTSTR, LPCTSTR (so Unicode and not Unicode), even a CString, or a char[1024] or a char * (I know some of these solutions are redundant) passing each time the address of the string to the first app, and tried every possible configuration of typecasts in the receiving function, but I can't seem to retrieve the sent string (most time, when the casts make sense, I have "IIIIIIIIIIIIIIIIIIIIIIIIIIIIII..." in the buff). And the Send instead of Post makes sure the string does not get destroyed before I read it from memory.
The weirdest thing is that if I replace the CString, or the LPCTSTR or what in the App2 with :
::SendMessage(WM_USER_2NDOPEN,(WPARAM)"RaGE",0);
Then I can retrieve the string without any problem, whatever the format and typecast I use in the receiving function in App1. 
My temporary solution is that I save the filename in a text file on the disk in C:\\Temp in App2, send the message and retrieve the name by reading it frim the file in App1. But I think this solution really sucks. 
I'd like to do it the right way, and I'm sure it _is_ possible to send a string using a windows message...
Can you help me ?
~RaGE();
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Hi,
I need to show different tooltips for different positions in the same window.How to implement this.
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