Wierd Hex Output

[mike.jenkins]

Hi Guys,

This is my first post here. I have this code and it does everything i want to but prints a "ffffff" infront of the output for some reason. Can you let me know why it is doing that and how to get around it?

The code is:

#include<stdio.h>

void main() {
int j=51712,*y;
char a, *z;
y=&j;
printf ("Size of an Integer in UltraSPARC-IIIi is %d bytes\n", sizeof(j));
printf ("Size of a Character in UltraSPARC-IIIi is %d byte\n", sizeof(a));
printf ("Address of variable = %x\n", y);
printf ("--------------------------------------\n");
z=(char *)y;
printf ("Address\t\tValue\n");
printf ("--------------------------------------\n");
printf ("%x\t %02x\n", z, *z);
printf ("%x\t %02x\n", z+1, *(z+1));
printf ("%x\t %02x\n", z+2, *(z+2));
printf ("%x\t %02x\n", z+3, *(z+3));
printf ("Value of varible is %d and is %x in hex\n", j,j);
}

And the output is:


Size of an Integer in UltraSPARC-IIIi is 4 bytes
Size of a Character in UltraSPARC-IIIi is 1 byte
Address of variable = ffbffd54
--------------------------------------
Address Value
--------------------------------------
ffbffd54 00
ffbffd55 00
ffbffd56 ffffffca
ffbffd57 00
Value of varible is 51712 and is ca00 in hex



Now i dont know why it is prepending that "ffffff" infront of "ca"

Thanks for all the help

Thanks
Mike

[matsp]

That's because you are translating a signed char into a signed integer, and as %x is treating the value as unsigned, you get a large positive number instead of a small negative one.

--
Mats

[mike.jenkins]

Oh. Thanks a lot for the reply

Then how do i fix that?

Thanks
Mike

[dwks]

Tell the compiler to cast the value to unsigned before you pass it to printf().

printf ("%x\t %02x\n", z+2, (unsigned)*(z+2));

Suggestion: don't use void main. cpwiki.sf.net/Void_main

[master5001]

printf ("%x\t %p\n", z+2, *(z+2));

[matsp]

printf ("%x\t %p\n", z+2, *(z+2));

You mean:

printf ("%p\t %x\n", z+2, *(z+2));

And strictly sticking to the standard:

printf ("%p\t %x\n", (void *)(z+2), *(z+2));

--
Mats

[master5001]

I did mean that. Swift and careless, that is my motto. Thanks Mats.

[Elysia]

I like:

printf("%p\t %x\n", (void*)&z[2], (unsigned)z[2]);

[master5001]

I also like titles that spell weird correctly.