Using reinterpret_cast

05-11-05, 03:26 AM

I am using a C library in my C++ program. I open a file for reading
in binary populating a char buffer. I pass this buffer to the C funtion.
When it is done I write the buffer to my ofstream file.
I want this fucntion to work on 32bit and PPC 32bit systems
as well as 64 bit systems. Any issues?

Is the following ok?

-----------------------------------------------------------------
bool ProcessFile(std::string sFileIn, std::string sFileOut)
{
// Will be set by library function
unsigned char ucSpec[128];

/* open file for reading in binary mode */
std::ifstream infile;
std::ofstream outfile;
infile.open(sFileIn.c_str(), std::ios::in | std::ios::binary);
outfile.open(sFileOut.c_str(), std::ios::out | std::ios::binary);

/* set cursor to the beginning of the file */
infile.seekg(0, std::ios::beg);
char buf[512];

// Write the ucSpec first
outfile.write(reinterpret_cast<const char *>(ucSpec), 128);

while (!infile.eof())
{
infile.read(buf, sizeof(buf));
OldCFunction(reinterpret_cast<unsigned char
*>(buf),cData,infile.gcount(),&pSpec);
outfile.write(reinterpret_cast<const char *>(cData), infile.gcount());
}

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

return true;
}

05-11-05, 09:18 AM

Kim Gräsman

Hello NA,

> infile.read(buf, sizeof(buf));
> OldCFunction(reinterpret_cast<unsigned char
> *>(buf),cData,infile.gcount(),&pSpec);
> outfile.write(reinterpret_cast<const char *>(cData),

This is the only thing that jumps out at me. What is cData? Can it safely
be casted to a 64-bit const char*?

If you're using Visual Studio 2003, you can enable the /Wp64 compiler switch,
and it will warn for 64-bit-unsafe constructs. It doesn't catch as much as
the 64-bit compiler does, but it gives you some idea.

05-11-05, 02:45 PM

"Kim Gräsman" <kim> wrote in message

>> infile.read(buf, sizeof(buf));
>> OldCFunction(reinterpret_cast<unsigned char
>> *>(buf),cData,infile.gcount(),&pSpec);
>> outfile.write(reinterpret_cast<const char *>(cData),
>
> This is the only thing that jumps out at me. What is cData? Can it safely
> be casted to a 64-bit const char*?

cData is declared as an unsigned char plaintext[512]

05-11-05, 02:49 PM

> cData is declared as an unsigned char plaintext[512]

That should read unsigned char cData[512]
excuse me...

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