Experimental Physics and Industrial Control System
Subject: |
[Bug 1740426] Re: portable printf() spec for size_t, long long, and others |
From: |
Martin Konrad via Core-talk <[email protected]> |
To: |
[email protected] |
Date: |
Tue, 07 Jan 2020 14:53:05 -0000 |
Mark, you're right, MSVC supports %z for size_t (which is certainly
preferred over the Microsoft-specific %I). This is supported at least
since VS 2015 (https://docs.microsoft.com/en-us/cpp/c-runtime-library
/format-specification-syntax-printf-and-wprintf-functions?view=vs-2015
#size-prefixes-for-printf-and-wprintf-format-type-specifiers). But I'm
not aware of a sane portable way of writing
int64_t i = 42;
printf("Works on Windows only: %I64d\n", i);
other than
printf("Works on all C99-compatible platforms: %"PRId64"\n", i);
Sure the following works
printf("Works on all C99-compatible platforms: %lli\n", (long long)i);
but I always have to pull up the standard to be sure the type I'm
casting to has sufficient size on all platforms. And it also requires
C99.
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https://bugs.launchpad.net/bugs/1740426
Title:
portable printf() spec for size_t, long long, and others
Status in EPICS Base:
Triaged
Bug description:
I've been in the habit of using '%lld' and '%zu' to print 'long long'
and 'size_t' respectively. However, the windows world needs '%I64d'
and '%Iu' instead. It would be nice to have compatibility macros for
this.
stdint.h/inttypes.h has a convention for this for the standard fixed
width types. eg. PRIx32 for 'uint32_t'. This is used like:
> printf("%"PRIx32"\n", (uint32_t)42);
http://en.cppreference.com/w/c/types/integer
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