（C ++）无法将十六进制写入.dat文件

Question

My program is pretty long and complex so I cannot explain it all, I will try to just explain my current situation, however.

I have a .dat file (729 of them but only 1 for this example) and I need to overwrite THE WHOLE FILE (even if my new data is smaller than the current data) with a couple strings containing hex values.

Here is a snippet from my program:

ofstream xbox_final(xboxit->c_str(), ios::binary);

//other stuff

xbox_final.write("0a00000a00054c6576656c070006426c6f636b7300008000", 48);
xbox_final.write(new_bytes, new_bytes.length());
xbox_final.write(xboxbytes, xboxbytes.length());
xbox_final.close();

"xboxit->c_str()" in the ofstream is there because I'm inputting and outputting a BUNCH of files from a file list and this was necessary but gives me no errors, if that makes sense.

The strings "new_bytes" and "xboxbytes" contains hex values (000007000a0445 etc...)

For now my program has just been writing to a text document. I need it to write that hex data in that order to the .dat file.

I did some searching around and this fixes the const char problem:

//other stuff

string header("0a00000a00054c6576656c070006426c6f636b7300008000");

WriteStr2BinFh( header, xbox_final);
WriteStr2BinFh( new_bytes, xbox_final);
WriteStr2BinFh( xboxbytes, xbox_final);

//other stuff

void WriteStr2BinFh( const std::string& St, std::ostream &out ) 
{
    out.write( St.c_str(), St.size() );
}

Creating new .dat files somewhere else is also an acceptable option.

I JUST CAN'T WRITE THE HEX VALUES, THEY ALWAYS SHOW UP AS TEXT IN THE DAT FILE.

Any help would be appreciated :)

Answer 1

A way to "easily" do that while keeping your current "model" would be to put "\\x" in front of every of your hex value in your string. The compiler will then treat them as actual values, and not as a pair of characters.

What I mean is :

std::cout << "4A4A" << std::endl;

would output :

4A4A

whereas

std::cout << "\\x4A\\x4A" << std::endl;

would output:

JJ

since 0x4A is the hexadecimal value for the ascii character J . Of course, the implications would be the same if you were writing this string to a file.

If you want to continue using a string to store it, you'll need to change the constructor since your string will contain the value 0 .

string header("your_hex_chain", number_of_bytes_in_your_chain); // \\x00 is one byte, for example

It would, however, be much easier to use a struct to store the values of your header, and write if directly to the .dat file. But I don't know much more about what you're trying to do, so...