printf() formatting for hex uint32_t without missing zeros. (in c89)

Wanted to print uint32 hex.
Tried "PRIx32", looked bad to me:

967407c0 23 4481d55f ffffff52 de3cd140
2fc aa7363cf fffff40d 563270c0 2b86


So... tried this. Dirty but worked:

/*******************************************************************************
Print a digit in hex.
*******************************************************************************/
void mpal_digit_t_print_hex(
mpal_digit_t * input)
{
uint8_t p_1, p_2, p_3, p_4, p_5, p_6, p_7, p_8;

p_1 = (uint8_t)(((*input) << 0) >> 28);
p_2 = (uint8_t)(((*input) << 4) >> 28);
p_3 = (uint8_t)(((*input) << 8) >> 28);
p_4 = (uint8_t)(((*input) << 12) >> 28);
p_5 = (uint8_t)(((*input) << 16) >> 28);
p_6 = (uint8_t)(((*input) << 20) >> 28);
p_7 = (uint8_t)(((*input) << 24) >> 28);
p_8 = (uint8_t)(((*input) << 28) >> 28);

printf(" %" PRIx8 "%" PRIx8 "%" PRIx8 "%" PRIx8 "%" PRIx8 "%" PRIx8 "%"
PRIx8 "%" PRIx8 "", p_1, p_2, p_3, p_4, p_5, p_6, p_7, p_8);
return;
}


Output:

61dd90ef ff6df47e a0a9abc0 011d7394 2311761f
f4402427 5c44ca40 0f86aba7 6aa5194f ecb9ed1e


Is there an elegant way to do this in c?

1 Answer
1

Those "symbolic" printf specifiers like PRIx32 are designed to be used with extra flags, if you need them. So you can do something like this:

PRIx32

printf("%08" PRIx32, hexval);


After string concatenation, this will typically turn into either %08x or %08lx. 8 specifies you want (at least) 8 digits, and 0 specifies 0-padding.

%08x

%08lx

8

0

x

printf("%.8" PRIx32, hexval);

0

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