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Problem with writing hex values

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Join Date: Nov 2008

Posts: 8

Reputation: replic is an unknown quantity at this point

Solved Threads: 0

replic

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Newbie Poster

Problem with writing hex values

Feb 25th, 2009

Hi everyone,
i wrote this small app and it works fine but it erases everything up to the offset and everything after it.
Anyone knows how to avoid that?

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <fstream>
 
int main()
{
	int hex = 0x75;
	std::ofstream f("sample.exe", std::ios::binary);
	f.seekp(1169, std::ios::beg);
	f.write(reinterpret_cast<const char *>(&hex), 2);
	f.close();
	return 0;
}
#include <iostream>
#include <fstream>

int main()
{
	int hex = 0x75;
	std::ofstream f("sample.exe", std::ios::binary);
	f.seekp(1169, std::ios::beg);
	f.write(reinterpret_cast<const char *>(&hex), 2);
	f.close();
	return 0;
}

regards

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Join Date: Aug 2007

Posts: 1,679

Reputation: vmanes is a splendid one to behold

Solved Threads: 193

vmanes

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Posting Virtuoso

Re: Problem with writing hex values

Feb 25th, 2009

also use mode std::ios::ate (AT End)

The default mode for ofstream opening is std::ios::trunc, (TRUNCate), which deletes any previous content of the file. ios::ate preserves the file, allows you to move the file pointer anywhere within the current content.

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Join Date: Nov 2008

Posts: 8

Reputation: replic is an unknown quantity at this point

Solved Threads: 0

replic

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Newbie Poster

Re: Problem with writing hex values

Feb 27th, 2009

It still doesn't work using this code.
It produces the same error again.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <fstream>
 
int main()
{
      int hex = 0x75;
      std::ofstream f("sample.exe", std::ios::binary | std::ios::ate);
      f.seekp(1169, std::ios::beg);
      f.write(reinterpret_cast<const char *>(&hex), 2);
      f.close();
      return 0;
}
#include <iostream>
#include <fstream>
 
int main()
{
      int hex = 0x75;
      std::ofstream f("sample.exe", std::ios::binary | std::ios::ate);
      f.seekp(1169, std::ios::beg);
      f.write(reinterpret_cast<const char *>(&hex), 2);
      f.close();
      return 0;
}