Problem Reading a file?

[sigmablack]

Hello, i am trying to read a file that contains Unicode Characters..

char * buffer;
  long size;

  ifstream infile ("old.exe",ifstream::binary);
  ofstream outfile ("new.exe",ofstream::binary);

  // get size of file
  infile.seekg(0,ifstream::end);
  size=infile.tellg();
  infile.seekg(0);

  // allocate memory for file content
  buffer = new char [size];

  // read content of infile
  infile.read (buffer,size);
  CString (str(buffer));
  str.Replace("OLD","NEW");
  // write to outfile	
  outfile.write(str,size);
  
  // release dynamically-allocated memory
  delete[] buffer;

  outfile.close();
  infile.close();

But when i cast from char array to CString all the information is lost (because of the presence of unicode characters)
i must cast to CString so that i can perform string replace function..
i have tried using _T() but it wont work..
please help
NOTE:I AM USING VC++ 6 MFC

[modoran]

std::wstring also has search/replace functions if your file is utf-16 le encoded. If it is not, but you know the encoding, use MultiByteToWideChar() API to convert (in memory) first to a Unicode (UTF-16) string.

Beware that you have a memory buffer there which is not null terminated.

[sigmablack]

wstring does not work either..
I can never be sure about the encoding.. because i want to replace strings in an exe file..
any idea what i need to do/read?
thanks for replying

[Peter87]

You have to know the encoding, otherwise there is no way you can handle it correctly.

[modoran]

If you want to "replace strings in a exe file", then just open a file in binary mode, copy the buffer to a std::string using assign() method (this can handle null characters just fine), perform the replace and write the string to a new file using std::ostream.write() method and std::string.data() as buffer.

Beware that this could give you unexpected results though, better use a resource editor.

[sigmablack]

thanks modoran.. now i have an idea of where to work on..
yeah, i have done this before using char array and alot of if statements.. :D
just wanted to follow a better method by using replace function but so far i am not able to read/copy the buffer to a string/wstring/cstring because of the null characters present in an exe file..
i hope the assign method will work fine.. i will return soon after trying it out.. :)
Regards

[sigmablack]

i don't want to use third party software, because i am creating an MFC application that replaces strings of exe files..
like in a "Hello World" program, change "Hello" to "Screw"..

[sigmablack]

copy the buffer to a std::string using assign() method

modoran, i have tried this code, but i cannot get it to work properly.. would you please correct me..

#include <fstream>
#include <iostream>
#include <string>
using namespace std;

int main()
{
	ifstream fs;
	fs.open ("1.exe", ios::binary);
	if (fs.fail()) 
	{
		cerr << "Failed to open file!\n";
		return 1;
	}
	fs.seekg(0, ios::end);
	size_t i = fs.tellg();
	char* buf = new char[i];
	fs.seekg(0, ios::beg);
	fs.read (buf, i);
	fs.close();
	string s;
	s.assign (buf, i);//is this the right way to assign
	delete [] buf;
	cout << s.data() << endl;//same old problem only a few chars printed
	
	return 0;
	
}

would you please provide a sample code

[Peter87]

What happens if you change line 24 to cout << s << endl;?

[sigmablack]

same.. the problem is with casting from char * buf to string s (line 22) :s
i must find a way to read mutliple Null Characters into a string..

[Peter87]

How do you know line 22 is the problem? Isn't s.size() same as i?

If s.size() == i I think that the problem is that std::cout can't handle the null characters. You could try using a loop to output all the characters in the string except the null characters.

for (char c : s)
{
	if (c != '\0')
	{
		std::cout << c;
	}
}
std::cout << std::endl;

[sigmablack]

well std::cout handles the null characters pretty well when i do this

ifstream fs;
	fs.open ("1.exe", ios::binary);
	if (fs.fail()) 
	{
		cerr << "Failed to open file!\n";
		return 1;
	}
	fs.seekg(0, ios::end);
	size_t i = fs.tellg();
	char* buf = new char[i];
	fs.seekg(0, ios::beg);
	fs.read (buf, i);
	fs.close();
        cout<<buf;//where buf is a char array 

thanks for your time, could you think of any other way..?
also the code you gave does not work for me either.. which makes me think if i am some how able to store multiple NULL characters in a string someway then i can accomplish my goal..

[sigmablack]

thanks modoran for giving me the correct idea and Peter you too for pointing out the mistake (you were right about cout)
this codes works like a charm thank you guys, great to have you around

#include <fstream>
#include <iostream>
#include <string>
using namespace std;
#include<windows.h>

int main()
{
	ifstream fs;
	fs.open ("1.exe", ios::binary);
	if (fs.fail()) 
	{
		cerr << "Failed to open file!\n";
		return 1;
	}
	fs.seekg(0, ios::end);
	size_t i = fs.tellg();
	char* buf = new char[i];
	fs.seekg(0, ios::beg);
	fs.read (buf, i);
	fs.close();
	string s;
	s.assign (buf, i);
	ofstream file;
	file.open("new.exe",ios::out);
	file.write(s.data(),s.size());//shoud i use s.size() or s.length()

	return 0;

	
}

please answer one last question, in the 2nd last line should i use size() or length?
is there anyother way i could make this code better?
thanks again

[Peter87]

should i use size() or length?

Both do the same thing so it doesn't matter.