Printing out in hex value

[kiros88]

Im using an 8 byte value and trying to print it out using
printf("%02X\n", variable);
but I can only get 4 bytes to print out how do i print out all 8 bytes
the variable is a pointer (void*)

[dwks]

The printf format specifier %p is specially intended to print pointers.

Otherwise, you could use

printf("%02lX\n", variable);

%d and %x (and %o) take unsigned integers, I believe. Just as %d can print longs with an extra "l" (lowercase "L"), so can %x and %o. That's my understanding of it, anyway.

[bithub]

The printf format specifier %p is specially intended to print pointers.

Otherwise, you could use

printf("%02lX\n", variable);

%d and %x (and %o) take unsigned integers, I believe. Just as %d can print longs with an extra "l" (lowercase "L"), so can %x and %o. That's my understanding of it, anyway.

Hmm, shouldn't that be

printf("%02llX\n", variable);

instead?

EDIT: oops, I missed the part where the type is a void pointer. I was assuming a 64 bit variable on a 32 bit system.

[dwks]

Umm . . . yeah, oops. Also, if you're working on Windows, the runtime might not support "ll".

The %x (hex int format) printf modifier will not work as expected on a 64-bit Windows operating system. It will only operate on the first 32 bits of the value that is passed to it.
* Use %I32x to display an integer on a Windows 32-bit operating system.
* Use %I64x to display an integer on a Windows 64-bit operating system.
* The %p (hex format for a pointer) will work as expected on a 64-bit Windows operating system.

From Common Visual C++ 64-bit Migration Issues

[bithub]

Yeah, %p should be used to print pointer values.

[dwks]

Agreed. I like how they list the most portable solution last.

[laserlight]

That said, in theory the pointer's value need not be printed out in hexadecimal representation when using the %p format specifier since that detail is implementation defined. Also, in other cases, if the pointer were not a pointer to void, it should be casted to pointer to void when used with %p.