strlen man-page misinformation
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Hello Alan,
Quoted 4 lines · Alan Aversa
Hello,
The 2015-08-08 strlen man-page is incorrect. Here's a diff:
Quoted 9 lines
--- a/man3/strlen.3
+++ b/man3/strlen.3
@@ -45,7 +45,7 @@ excluding the terminating null byte (\(aq\\0\(aq).
.SH RETURN VALUE
The
.BR strlen ()
-function returns the number of bytes in the string +function returns the number of *characters* in the string that precede the terminating null character
I went for a simpler change: s/bytes/characters/
Quoted 9 lines
.IR s .
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
@@ -60,7 +60,7 @@ T{
T} Thread safety MT-Safe
.TE
.SH CONFORMING TO
-POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
+POSIX.1-2001, POSIX.1-2008, C89, C99, C11, SVr4, 4.3BSD.Fixed.
Quoted 9 lines
.SH SEE ALSO .BR string (3), .BR strnlen (3),Page 392 (PDF p. 390, §7.24.6.3) of the C11 standard
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf> says:The *strlen* function returns the number of characters that precede the terminating null character.
Thanks for the report. Interesting, POSIX.1 still uses the term "bytes" the spec.
Cheers,
Michael
Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
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Am 18.02.2016 14:12, schrieb Michael Kerrisk (man-pages):
Quoted 17 lines
Hello Alan,
Quoted 4 lines · Alan Aversa
Hello,
The 2015-08-08 strlen man-page is incorrect. Here's a diff:
Quoted 9 lines
--- a/man3/strlen.3
+++ b/man3/strlen.3
@@ -45,7 +45,7 @@ excluding the terminating null byte (\(aq\\0\(aq).
.SH RETURN VALUE
The
.BR strlen ()
-function returns the number of bytes in the string +function returns the number of *characters* in the string that precede the terminating null character
Quoted 1 line
I went for a simpler change: s/bytes/characters/
For my understanding this is wrong. 1 character may be represented by 2 or more bytes (utf8). see this example, the string (test) is 3 characters long and takes 6 bytes space.
did i miss something ? did the specification of character change ?
re,
wh
#include <stdio.h>
#include <string.h>
int main()
{
char *test="ÖÄÜ";
int i;
int len=strlen(test);
printf("strlen=%d\n",len);
for(i=0;i<len;i++)
printf("%02x\n",(unsigned char)*(test+i));
return 0;
}output:
strlen=6
c3
96
c3
84
c3
9c
Quoted 23 lines
Quoted 10 lines
.IR s . .SH ATTRIBUTES For an explanation of the terms used in this section, see @@ -60,7 +60,7 @@ T{ T} Thread safety MT-Safe .TE .SH CONFORMING TO -POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD. +POSIX.1-2001, POSIX.1-2008, C89, C99, C11, SVr4, 4.3BSD.Fixed.
Quoted 9 lines
.SH SEE ALSO .BR string (3), .BR strnlen (3),Page 392 (PDF p. 390, §7.24.6.3) of the C11 standard
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf> says:The *strlen* function returns the number of characters that precede the terminating null character.
Quoted 8 lines
Thanks for the report. Interesting, POSIX.1 still uses the term "bytes" the spec.
Cheers,
Michael
--
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A message that is not in the archive (sent off-list or not yet received): [email protected]
Quoted 20 lines · walter harms
Am 18.02.2016 14:12, schrieb Michael Kerrisk (man-pages):
Quoted 17 lines
Hello Alan,
Quoted 13 lines · Alan Aversa
Hello,
The 2015-08-08 strlen man-page is incorrect. Here's a diff:
--- a/man3/strlen.3
+++ b/man3/strlen.3
@@ -45,7 +45,7 @@ excluding the terminating null byte (\(aq\\0\(aq).
.SH RETURN VALUE
The
.BR strlen ()
-function returns the number of bytes in the string +function returns the number of *characters* in the string that precede the terminating null character
Quoted 7 lines
Quoted 1 line
I went for a simpler change: s/bytes/characters/
For my understanding this is wrong. 1 character may be represented by 2 or more bytes (utf8). see this example, the string (test) is 3 characters long and takes 6 bytes space.
did i miss something ? did the specification of character change ?
[...]
Either "bytes" or "characters" would be correct. POSIX says "bytes"; ISO C says "characters".
See the definition of "character" in C11 3.7.1:
Quoted 1 line
bit representation that fits in a byte
On the other hand, 3.7 defines an (abstract) "character" as:
Quoted 2 lines
member of a set of elements used for the organization, control, or representation of data
It also defines the terms "multibyte character" (a sequence of one or more bytes representing a member of the extended character set) and "wide character" (a value of type wchar_t).
"Bytes" is less ambiguous, but "characters" matches the wording of the ISO C standard (and, in that context, refers to single-byte characters).
Signature · 5 lines
Keith Thompson <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html