aslamshikoh1
asked on
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
BYTE *buf = new BYTE[200];
buf=somedata ;
into a file,for eg "bytedata.dat"
please provide some good eg
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();
#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();
Don't forget to free your buffer
BYTE *buf = new BYTE[200];
delete [] buf;
Also, in C++ consider using std::string instead...
http://msdn2.microsoft.com/en-us/library/syxtdd4f(VS.80).aspx
http://msdn2.microsoft.com/en-us/library/syxtdd4f(VS.80).aspx
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;
}
ASKER
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->isA ctive_ && --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.
while(oEditStreamImpl->isA
{
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.
ASKER
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
write((char*)buf,200)
is it OK to do this
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SOLUTION
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>> 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 *
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 *
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.
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.
#include <stdio.h>
//...
BYTE *buf = new BYTE[200];
//...
FILE* p = fopen(bytedata.dat","wb");
fwrite(buf, 1, 200);
fclose(p);