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Write a Byte array to a file

How can i write a byte array,for eg:

BYTE *buf = new BYTE[200];
buf=somedata ;

into a file,for eg "bytedata.dat"

please provide some good eg
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aslamshikoh1
Asked:
aslamshikoh1
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2 Solutions
 
jkrCommented:
The easiest way would be to

#include <stdio.h>

//...


BYTE *buf = new BYTE[200];

//...

FILE* p = fopen(bytedata.dat","wb");

fwrite(buf, 1, 200);

fclose(p);
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jkrCommented:
Or, more on the C++ side:

#include <fstream>
using namespace std;


BYTE *buf = new BYTE[200];

//..


ofstream os("bytedata.dat", ios_base::out | ios_base::binary);

os.write(buf,200);

os.close();
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evilrixSenior Software Engineer (Avast)Commented:
Don't forget to free your buffer
BYTE *buf = new BYTE[200];
delete [] buf;

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evilrixSenior Software Engineer (Avast)Commented:
Also, in C++ consider using std::string instead...
http://msdn2.microsoft.com/en-us/library/syxtdd4f(VS.80).aspx
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evilrixSenior Software Engineer (Avast)Commented:
An example using strings and streams...
#include <string>
#include <iostream>
#include <fstream>
 
int main()
{
	// The data we wish to write to file
	std::string sData("Hello world");
 
	// Open the file as a stream (destructor will close for us)
	std::ofstream ofs("c:\\temp\\data.txt");
 
	// If file was opened ok...
	if(ofs.is_open())
	{
		// Write out data to it
		ofs << sData;
 
		// If write error then report it
		if(!ofs.good())
		{
			std::cerr << "Failed to write data" << std::endl;
		}
	}
 
	return 0;
}

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aslamshikoh1Author Commented:
Ok i got it but i have a continuous stream of bytes to write to a file.Its a thread which has a while loop like this:

while(oEditStreamImpl->isActive_  && --count)
      {
            

            ofstream os("bytedata.dat", ios_base::out | ios_base::binary);
                 os.write(buf,200);
}

os.close()

so how can i append the data to end of the file,like something to do with the file pointer,right now data is getting overwritten.
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aslamshikoh1Author Commented:
also write(buf,200) complains about not able to accept a byte,i guess a char array is what it accepts,so im just casting it like

write((char*)buf,200)

is it OK to do this
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evilrixSenior Software Engineer (Avast)Commented:
Try: -
ofstream os("bytedata.dat", ios_base::binary);
while(oEditStreamImpl->isActive_  && --count)
{
    os.write(reinterpret_cast<char *>(buf),200);
}
os.close();

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jkrCommented:
>>is it OK to do this

yes, absolutely, since the stream is openend as binary.
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evilrixSenior Software Engineer (Avast)Commented:
>> is it OK to do this
Yes, a stream expects a char * but you can cast any pointer type to that as long as you specify correctly the number of chars when writing it out. It helps if you just think of it as writing signed bytes.

NB. a wide stream expects wchar_t *
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Infinity08Commented:
btw, this :

        BYTE *buf = new BYTE[200];
        buf=somedata ;

creates a memory leak ... you're overwriting the pointer to the allocated 200 bytes with a new value.
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