[C] fprintf writing ascii instead of binary

[Richard Davison]

SOLVED see my next post in this thread

I feel so dumb for not being able to figure this out. Does it have anything to do with the double quotations?

FILE *file;
file = fopen("test", "wb");
fprintf(file, "%d", 0x000000FF);
fclose(file);

then I call hexdump -C test

and I see

00000000  32 35 35

instead of

00000000  FF 00 00 00

Edited August 3, 2009 by Richard Davison

[Lant]

I'm not that experience in C but aren't you writing the string "255" to the file?

So the following would do what you want:

fprintf(file, "%c", 0xFF);

[Pablo2008jedi]

http://msdn.microsoft.com/en-us/library/hf...28VS.80%29.aspx

I think you use %x instead of %d

[Richard Davison]

I think I overlooked the fwrite() function.

@Lant, if I just used %c, then yeah, FF would show up, but the remaining zeros would get lost. I would be writing 1 byte rather than the 4 bytes I want to write with an int.

@Pabs(Sco), with %x the hexdump gives me 66 66 which the ascii equivalent to FF

edit:

I think I've just been using the wrong function. I should probably be using fwrite instead of fprintf

edit again:

this code works

#include <stdio.h>

void main(void)
{
	int i = 0x000000FF;
	FILE *file;
	file = fopen("test", "wb");
	fwrite(&i, sizeof(int), 1, file);
	fclose(file);
}

it spits out ff 00 00 00

good night... *yawns*

Edited August 3, 2009 by Richard Davison