-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chuck,
On 10/8/2009 8:27 PM, Caldarale, Charles R wrote: >> From: Christopher Schultz [mailto:ch...@christopherschultz.net] >> Subject: Re: [OT] JNI problem >> >> C99 allows /dynamic/ size determination: > > Sounds like a flaw in the article; it can't possibly be true, since > there is no standard-defined API to discover the size of a malloc'd > item; sizeof is *always* a compile-time operation. Agreed. It sounds like the article's terminology (or our interpretation of it) is incorrect. C99 probably allows this: char s[20]; sizeof s; To yield 20, while strict, old-skool C would yield whatever "sizeof char*" would. In any case, it's always best to use strlen() to figure out how many chars are in a string. This will also be better when working with different character sets, as one might search for invocations of the strlen() function to change them to, say, wcslen() to handle wide-character strings. It would be awkward and tedious to search for use of the sizeof operator to change from single-byte-character to wide-character strings. > The only situation > where it is not a compile-time /constant/ is if the size of the array of > interest is dependent on the value of a function parameter: > > int func(int val) { > char arr[val + 6]; > return sizeof arr; /* returns val + 6 */ > } > > This is not really dynamic allocation. I guess you mean dynamic sizing and not dynamic allocation. I'm honestly surprised that this: #include <stdio.h> int func(int val) { char arr[val + 6]; return sizeof arr; } int main(int argc, char *argv[]) { printf("%d\n", func(1)); printf("%d\n", func(2)); printf("%d\n", func(3)); } Prints this: 7 8 9 on my system (gcc 4.2.1). It appears that: sizeof arr compiles to the equivalent of: val + sizeof char[6] That's a pretty clever compiler. Whatever happened to the days when compilers found ways to make your life miserable instead of actually helping you out? ;) - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkrPYUQACgkQ9CaO5/Lv0PAx/ACfUpt4qIgV/d/VCWpGbYbIgbjf MKMAnje7v2MaP0RuifSOrA1B5P1CjOaC =DDDO -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
