On Wed, 27 Jul 2005, Glynn Clements wrote:
Holger Kiehl wrote:
The problem I have with this is how do I use this with printf() or fprintf()?
What do I use: %u, %lu or %llu? Does C99 provide a solution here?
7.8 Format conversion of integer types <inttypes.h>
[#1] The header <inttypes.h> includes the header <stdint.h>
and extends it with additional facilities provided by hosted
implementations.
[#2] It declares four functions for converting numeric
character strings to greatest-width integers and, for each
type declared in <stdint.h>, it defines corresponding macros
for conversion specifiers for use with the formatted
input/output functions.169)
Forward references: integer types <stdint.h> (7.18).
7.8.1 Macros for format specifiers
[#1] Each of the following object-like macros170) expands to
a character string literal containing a conversion
specifier, possibly modified by a length modifier, suitable
for use within the format argument of a formatted
input/output function when converting the corresponding
integer type. These macro names have the general form of
PRI (character string literals for the fprintf family) or
SCN (character string literals for the fscanf family),171)
followed by the conversion specifier, followed by a name
corresponding to a similar type name in 7.18.1. For
example, PRIdFAST32 can be used in a format string to print
the value of an integer of type int_fast32_t.
[#2] The fprintf macros for signed integers are:
PRId8 PRId16 PRId32 PRId64
PRIdLEAST8 PRIdLEAST16 PRIdLEAST32 PRIdLEAST64
PRIdFAST8 PRIdFAST16 PRIdFAST32 PRIdFAST64
PRIdMAX PRIdPTR
PRIi8 PRIi16 PRIi32 PRIi64
PRIiLEAST8 PRIiLEAST16 PRIiLEAST32 PRIiLEAST64
PRIiFAST8 PRIiFAST16 PRIiFAST32 PRIiFAST64
PRIiMAX PRIiPTR
[#3] The fprintf macros for unsigned integers are:
PRIo8 PRIo16 PRIo32 PRIo64
PRIoLEAST8 PRIoLEAST16 PRIoLEAST32 PRIoLEAST64
PRIoFAST8 PRIoFAST16 PRIoFAST32 PRIoFAST64
PRIoMAX PRIoPTR
PRIu8 PRIu16 PRIu32 PRIu64
PRIuLEAST8 PRIuLEAST16 PRIuLEAST32 PRIuLEAST64
PRIuFAST8 PRIuFAST16 PRIuFAST32 PRIuFAST64
PRIuMAX PRIuPTR
PRIx8 PRIx16 PRIx32 PRIx64
PRIxLEAST8 PRIxLEAST16 PRIxLEAST32 PRIxLEAST64
PRIxFAST8 PRIxFAST16 PRIxFAST32 PRIxFAST64
PRIxMAX PRIxPTR
PRIX8 PRIX16 PRIX32 PRIX64
PRIXLEAST8 PRIXLEAST16 PRIXLEAST32 PRIXLEAST64
PRIXFAST8 PRIXFAST16 PRIXFAST32 PRIXFAST64
PRIXMAX PRIXPTR
Besides, what do I use for uint64_t in printf()?
The PRIu64 macro.
Thanks for the information!
Out of curiosity, why do you want an unsigned off_t anyhow?
I use it to store the number of bytes I have send to a certain host.
If this is unsigned there is no need to worry about an overflow and I can
always just add each file size transmitted. Just when I want to calculate
the transfer rate I need to watch out for an overflow.
Why not just use "long long" or "int64_t"?
If you're sending multiple files, I can't see any reason why the total
amount of data sent would depend upon sizeof(off_t).
You are right, that is a much better solution. Thanks!
If you're always using a 64-bit type, there isn't any reason to use
unsigned. I'm fairly certain that you aren't going to be sending more
than 2^63 bytes; even at 1Gbit/sec, that would take ~2000 years.
If you're using a 32-bit type, overflow is a realistic possibility
regardless of whether you use signed or unsigned.
Yes this is what happened to my surprise. On one platform off_t is only
32-bit and overflowed very quickly.
Holger
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