getchar for binary files

[ushtabalakh]

Hi there,
I've written the following code to print contents of a file,

I use it in command line like this.

toHex < sample.txt

it works for text files but not for binary files, I have to get the binary file as input stream; any ideas on how this could be possible? I'm looking for a getchar like function that would get binary characters too.


while((c=getchar()) != EOF && lines <= 1000) {
// Display 16 bytes per line
if (limit % 16 == 0)
{
if (limit!=0) //Printing a crlf after each 16 bytes except the first line
printf("\n");

//Printing a 4 digit line number in hex format
printf("%.4X: ",limit);
}
//Print the given character
printf("%.2X ", (int)c);
limit++;
}

 

[xwb]

stdin is opened as a text file. I don't know how you would force it to be a binary file. Easier if you pass the filename as a parameter and open it as a binary file.

 

[Salem]

Perhaps if you clarified "doesn't work" as well.

For example, did you declare your 'c' variable as a char (bad) or as an int (good).

Or perhaps you're getting a whole bunch of fffff printed when you try to print things with the high bit set?
In which case you should be casting your 'c' variable to unsigned.


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[ushtabalakh]

thanks for your answers

When c was defined as character it wasn't showing anything for binary files, now that I have changed it to unsigned it shows characters till a bye that is equal to 1A, and then stops going further.

I can't accept parameters and open the binary files it must be written this way.

Here's my new code:


unsigned c;
int limit = 0;
int lines=1000;

while((c=getchar()) != EOF && limit <= lines -1) {
// Display 16 bytes per line
if (limit % 16 == 0)
{
if (limit!=0) //Printing a crlf after each 16 bytes except the first line
printf("\n");

//Printing a 4 digit line number in hex format
printf("%.4X: ",limit);
}
//Print the given character
printf("%.2X ", (int)c);
limit++;
}

return 0;
}

 

[Salem]

I think you're out of luck then, since it seems your stdin is opened in "text mode". Historically, the "1A" byte value was used to mark the end of a text file, so I'm guessing that as soon as that appears, then EOF is signalled.

Which OS/Compiler are you using? There may be some non-standard API call to flip stdin into binary mode before you start reading from it.

BTW, c should be declared int, then cast to unsigned for printing.

Please use [code][/code] tags when posting code.


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[ushtabalakh]

Hi there
currently I'm using microsoft visual c++
but the final program will run under gcc and linux

thanks for the code tag I was really looking for that.

 

[Salem]

I suggest you try your program in the final environment then.
It should work just fine there.


--
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.

 

[ushtabalakh]

Yes it did work, thank you so much.