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class CA{
private:
int m_Var;
public:
CA(int x=0): m_Var(x){cout<<"1";}
bool operator < (const CA &obj2) { cout<<"2"; return (m_Var < obj2.m_Var) ? true : false;}
};
int main(void) {
CA obj1=2;
if(obj1 < 3){cout << "In If block" << endl;}
}
the output of this code is 112In If block .. i can understand the reason behind the first 1 and "2In If block" .. i dont understand when the second 1 is being called?
as per my understanding when (obj1<3) executes it may call obj1.operator<(3)
But constructor is being called but whats makes it to call?
kindly explain why the second 1 is being displayed?
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Member 3974347 wrote: as per my understanding when (obj1<3) executes it may call obj1.operator<(3)
Not actually. It is actually called like
obj1.operator<( CA(3));// A local temporary object is created here.
Here the integer 3 is automatically converted to a CA object by involking the constructor. Such conversions are called implicit conversions. You can prevent such conversions using the explicit keyword[^]
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You are so fast! 
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Well, I borrowed some monkeys[^] from Rajesh.
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Thanks. 
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Member 3974347 wrote: But constructor is being called but whats makes it to call?
Because constructor accepts a int.
Member 3974347 wrote: as per my understanding when (obj1<3) executes it may call obj1.operator<(3)
Your operator overload accepts const CA & but you specified the expression obj1<3, since type CA has a constructor which takes int, a temporary will be created by passing 3 to the constructor of CA and this is the reason for the second time constructor call.
Use explicit keyword to avoid the confusion.
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Thanks
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in turbo c on executing the program i get linked error and undefined symbol even for predefined functions like rectangle line etc... even the example programs given encounter the same problem..
please help
vicky
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vigneshvdm wrote: in turbo c on executing the program i get linked error and
undefined symbol even for predefined functions like rectangle line
These cannot happen when you execute your program. Can happen, however when you try to compile your sources.
vigneshvdm wrote: undefined symbol
You probably forget to include graphics.h that is required to compile when using graphic functions and data structures.
vigneshvdm wrote: i get linked error
You got linker error because you probably forget to link with graphics.lib.
See, for instance [^].
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]
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Dear all,
I have two lan cards.
So I have two ip address, too.
When I connect to server, how to get ip address of connected socket (clinet side NOT server side).
I could get ip address list of desktop using 'gethostbyname()'
But I didn't figure what ip address is current ip(lan card)
Do you have any solution?
Thanks.
cozyu
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Hi there how are u am fine and then to the point am a fresh student in some university and i have an assignment in modular c programing that work arijister of university the fuction must contain the student's nam, id number,nationality,father's name,occopation bed number.And am not any acces to do these am search many sits but am not get much for my problem pleas help me download the answer as you can and am went to say you do not worry about my grammer it is not my mother tounghthank you.
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seiyfu yesuf wrote: pleas help me download the answer
The answer to what? You haven't asked a question...
I'm assuming you haven't been given this project in the first week of your course, so you must have learned some programming before this. What have you done to make a start on it? What have you done in the way of system design? In programming?
There are three kinds of people in the world - those who can count and those who can't...
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Do your assignment yourself.
It is a crappy thing, but it's life -^ Carlo Pallini
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Try seraching for "C Tutorials" on Google, and look at some examples u will get an idea to start-up.
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Hi,
I managed to compile this audio recording code but the header is corrupt. I know this because I compared the header output from this program and a neat .wav file using HexEdit.
http://www.scribd.com/doc/16336997/CPP-Code
here is the code. I din't wanna put a 5 page code in this page. So uploaded to scribd.
I need to make changes to the header. Can anyone give me some direction?
Thanks
Niks
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It is giving so much noise that the audio it is recording is very unclear.
Thanks
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I dared to click on the link and had a look at the code. Anyway, nobody is going to debug the code for you, you'll have to do it yourself.
Alternatively, you can have a look at the several articles on this site about sound recording.
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Thanks. I actually did look at many articles and then asked the question.
Anyways, off to work
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<code>#include <stdio.h>
#include <conio.h>
#include <windows.h>
#include "aviriff.h"
#include <iostream>
#include <mmsystem.h>
using namespace std;
//WAV format def
int sps = 22050; // sample per seconds
int channels = 1; //numbers of channels
int bits = 8; //Bit rate. Why does it not works with 16?
int wav_length_sec = 60; //Rec length (sec)
int WAVBUFFERLENGTH((channels * bits * sps * wav_length_sec)/8);
WAVEFORMATEX g_WavFmt = {0};
//Wave header length
int HEADERLENGTH (sizeof(RIFFLIST) + sizeof(RIFFCHUNK) + sizeof(WAVEFORMATEX) + sizeof(RIFFCHUNK));
void InitWavFmt(void)
{
g_WavFmt.wFormatTag = WAVE_FORMAT_PCM;
g_WavFmt.nChannels = 1;
g_WavFmt.nSamplesPerSec = 8000;
g_WavFmt.wBitsPerSample = 16;
g_WavFmt.nBlockAlign = g_WavFmt.nChannels * g_WavFmt.wBitsPerSample / 8;
g_WavFmt.nAvgBytesPerSec = g_WavFmt.nChannels * g_WavFmt.wBitsPerSample / 8 * g_WavFmt.nSamplesPerSec;
g_WavFmt.cbSize = 0;
/*g_WavFmt.wFormatTag = WAVE_FORMAT_PCM;
g_WavFmt.nChannels = channels;
g_WavFmt.nSamplesPerSec = sps;
g_WavFmt.wBitsPerSample = bits;
g_WavFmt.nBlockAlign = 1;
g_WavFmt.nAvgBytesPerSec = g_WavFmt.nChannels * g_WavFmt.wBitsPerSample / bits * g_WavFmt.nSamplesPerSec;*/
// g_WavFmt.nBlockAlign = g_WavFmt.nChannels * g_WavFmt.wBitsPerSample / 8;
// g_WavFmt.nAvgBytesPerSec = g_WavFmt.nChannels * g_WavFmt.wBitsPerSample / bits * g_WavFmt.nSamplesPerSec;
// g_WavFmt.nAvgBytesPerSec = g_WavFmt.nSamplesPerSec * g_WavFmt.nBlockAlign;
g_WavFmt.cbSize = 0;
}
char* AddWavHdr(char *pinBuffer, int inWavLength)
{
BYTE *pWavHdr = NULL;
RIFFLIST *pRiffWave = NULL;
RIFFCHUNK *pRiffFmt = NULL;
RIFFCHUNK *pRiffData = NULL;
char* outWavBuffer = NULL;
if (NULL == pinBuffer)
{
return NULL;
}
pWavHdr = new BYTE[HEADERLENGTH];
if ( NULL == pWavHdr)
{
return NULL;
}
else
{
memset(pWavHdr, 0, sizeof(BYTE) * HEADERLENGTH);
}
pRiffWave = (RIFFLIST*)pWavHdr;
pRiffFmt = (RIFFCHUNK*)(pRiffWave + 1);
pRiffData = (RIFFCHUNK*)(((BYTE*)(pRiffFmt + 1)) + sizeof(WAVEFORMATEX));
pRiffWave->fcc = FCC('RIFF');
pRiffWave->cb = inWavLength + HEADERLENGTH - sizeof(RIFFCHUNK);
pRiffWave->fccListType = FCC('WAVE');
pRiffFmt->fcc = FCC('fmt ');
pRiffFmt->cb = sizeof(WAVEFORMATEX);
pRiffData->fcc = FCC('data');
// pRiffData->cb = inWavLength;
memcpy(pRiffFmt + 1, &g_WavFmt, pRiffFmt->cb);
outWavBuffer = (char*)new BYTE[inWavLength+HEADERLENGTH];
if (NULL == outWavBuffer)
{
return NULL;
}
else
{
memset(outWavBuffer, 0, sizeof(BYTE) * (inWavLength + HEADERLENGTH));
}
memcpy(outWavBuffer, pWavHdr, sizeof(BYTE) * HEADERLENGTH);
memcpy(outWavBuffer + HEADERLENGTH, pinBuffer, (sizeof(BYTE) * inWavLength));
return outWavBuffer;
}
void main ()
{
HWAVEIN hWavIn;
WAVEHDR WavHdr;
char *pBuffer = NULL;
char *pWavBuffer = NULL;
MMRESULT ret;
FILE *fpPCMFile;
FILE *fpWavFile;
MMTIME MMTime = {0};
unsigned int numwritten = 0;
MMTime.wType = TIME_BYTES;
InitWavFmt();
cout << "NumDev = " << waveInGetNumDevs() << endl;
if ( waveInGetNumDevs()==0)
{
cout << "Audio device not found!\n";
exit(0);
}
ret = waveInOpen(&hWavIn, WAVE_MAPPER, &g_WavFmt, 0, 0, WAVE_FORMAT_QUERY);
if (MMSYSERR_NOERROR != ret)
{
cout << "Unsupported WAV format.\n";
exit(0);
}
ret = waveInOpen(&hWavIn, WAVE_MAPPER, &g_WavFmt, 0, 0, CALLBACK_NULL);
if (MMSYSERR_NOERROR != ret)
{
exit(0);
}
pBuffer = (char*)malloc(WAVBUFFERLENGTH);
if ( NULL != pBuffer)
{
memset(pBuffer, 0, WAVBUFFERLENGTH);
}
else
{
exit(0);
}
WavHdr.lpData = pBuffer;
WavHdr.dwBufferLength = WAVBUFFERLENGTH;
WavHdr.dwBytesRecorded = 0;
WavHdr.dwUser = 0;
WavHdr.dwFlags = 0;
WavHdr.dwLoops = 1;
WavHdr.lpNext = 0;
WavHdr.reserved = 0;
ret = waveInPrepareHeader(hWavIn,&WavHdr,sizeof(WAVEHDR));
// res=waveInPrepareHeader(hWaveIn,&WaveHeader,sizeof(WAVEHDR));
if (MMSYSERR_NOERROR != ret)
{
free(pBuffer);
exit(0);
}
ret = waveInAddBuffer(hWavIn,&WavHdr,sizeof(WAVEHDR));
if (MMSYSERR_NOERROR != ret)
{
free(pBuffer);
exit(0);
}
cout <<"Press any key to start recording...\n";
_getch();
cout << "Recording now\n";
ret = waveInStart(hWavIn);
if (MMSYSERR_NOERROR != ret)
{
free(pBuffer);
exit(0);
}
cout << "Press any key to stop Recording\n";
_getch();
waveInGetPosition(hWavIn, &MMTime, sizeof(MMTime));
waveInReset(hWavIn);
// cout << "sizeof MMTime = " << sizeof(MMTime) << endl;
waveInUnprepareHeader(hWavIn,&WavHdr,sizeof(WAVEHDR));
waveInClose(hWavIn);
/*fpPCMFile = fopen("pcm","w");
if (NULL == fpPCMFile)
{
cout <<"Creating PCM file failed\n";
free(pBuffer);
exit(0);
}
numwritten = fwrite(pBuffer, sizeof(char), MMTime.u.cb, fpPCMFile);
cout <<"Recording done, %d bytes recorded, %d bytes written: " << MMTime.u.cb << endl << " numwritten: " << numwritten;
fclose(fpPCMFile);*/
pWavBuffer = AddWavHdr(pBuffer, MMTime.u.cb);
if ( NULL == pWavBuffer)
{
cout <<"Add header failed\n";
}
else
{
fpWavFile = fopen("testfile.wav", "w");
if (NULL == fpWavFile)
{
cout <<"Creating WAV file failed\n";
}
else
{
numwritten = fwrite(pWavBuffer, sizeof(char), sizeof(BYTE) * (HEADERLENGTH + MMTime.u.cb), fpWavFile);
// cout <<"%d bytes of WAV file written\n", numwritten;
fclose(fpWavFile);
free(pWavBuffer);
}
}
free(pBuffer);
_getch();
return;
}
here is the code. May be someone can give me directions.
Thanks
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I'm a greenhorn when it comes to Oracle and C++.
If I want to execute a simple "Select [Field1] from [table1]" bit of SQL from C++, how would I do that for Oracle?
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JaeBeam wrote: I'm a greenhorn when it comes to Oracle and C++.
If I want to execute a simple "Select [Field1] from [table1]" bit of SQL from C++, how would I do that for Oracle?
You might want to look at the Database Articles here on CodeProject.
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Perhaps, you may benefit from here.[^]
Or here for C only.[^]
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Hi
I have a project which I need to modify it to support wide character. There are so many text strings in the project. Is there an easy way to do this (add "_T()")?
Best regards,
modified on Thursday, June 11, 2009 3:56 PM
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The Find and Replace feature in Visual Studio will accept regular expressions:
Regular Expressions (Visual Studio)[^]
To search for single and double quoted literal string and replace them with the _T macro:
1.) Backup your project! I take no responsibility for the outcome.
2.) Open Find and Replace menu.
3.) Add the following text into the find box: {:q}
4.) Add the following to the replace box: _T(\1)
5.) Iterate through the matches and selectively replace your strings. I recommend avoiding the Replace All button as undo will probably not be available.
Note that #include statements and various other unwanted positive matches will occur with this method. You should make a backup of your project just in case something goes wrong.
Hope this helps,
-David Delaune
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