Differences between version 2 and predecessor to the previous major change of CPortabilityNotes.
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| Newer page: | version 2 | Last edited on Tuesday, January 25, 2005 9:57:02 pm | by PerryLorier | Revert |
| Older page: | version 1 | Last edited on Tuesday, January 25, 2005 12:29:09 pm | by JohnMcPherson | Revert |
@@ -7,7 +7,17 @@
[BSD]-style unixes uses flock(2), which uses "advisory" locks. Ie, a process with sufficient read or write permission can ignore the lock and read/write a file. [SysV]-style unixes use either advisory locks or "mandatory" locks (if enabled in the filesystem), and access them by the fcntl(2) command and a <tt>struct flock</tt> object.
A more portable way (POSIX 1003.1-2001) is to use the lockf(3) function from unistd.h, which will do the correct type of locking for the unix it is compiled on. (In Linux/GNU libc, this function is a wrapper around fcntl(2)).
+
+!!!printf types
+!64bitisms and fixed sized types
+If you have a fixed sized type (eg, uint64_t) and you want to use printf to display it, you need to know the real type of the integer. eg:
+ uint64_t x;
+ printf("%llu",x);
+This however will fail on 64bit machines as uint64_t is "long" not "long long". The best solution to this that I've found is to typecast it to the longer of the types and use that. eg:
+ uint64_t x;
+ printf("%llu",(long long unsigned)x);
+Better solutions solicited.
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Part of CategoryProgramming
