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Full Discussion: pointer arithmetic vs. strlen() & strnlen()?
Top Forums Programming pointer arithmetic vs. strlen() & strnlen()? Post 302280391 by jjinno on Monday 26th of January 2009 09:26:13 PM
Old 01-26-2009
Quote:
Originally Posted by shamrock
do you work in embedded systems???
Nope. I just happened to be helping somebody debug a seg-fault in their code caused by pointer-arithmetic error & we ended up in this "philosophical discussion".

His point was to suggest that if a "\0" made it into the string, the simple use of strlen() or strnlen() would not do "what he wants" (basically a simple socket-based string messenger). Trying to understand his point, I asked if what he was planning on sending/receiving strings with NULL characters in them... to which he responded quite obviously "No".

I was just trying to ascertain if there really was some performance/reliability/speed/efficiency to be gained in not using strlen() or strnlen(). I thought there legitimately might be, but now I am second-guessing, and simply thinking the guy is nuts to write his own function for something so simple... especially since he got it wrong
 

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LEARN ABOUT OPENDARWIN

strnlen

STRNLEN(3)						     Linux Programmer's Manual							STRNLEN(3)

NAME

       strnlen - determine the length of a fixed-size string

SYNOPSIS

       #include <string.h>

       size_t strnlen(const char *s, size_t maxlen);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       strnlen():
	   Since glibc 2.10:
	       _POSIX_C_SOURCE >= 200809L
	   Before glibc 2.10:
	       _GNU_SOURCE

DESCRIPTION

       The  strnlen()  function returns the number of characters in the string pointed to by s, excluding the terminating null byte (''), but at
       most maxlen.  In doing this, strnlen() looks only at the first maxlen characters in the string pointed to by s and never beyond s+maxlen.

RETURN VALUE

       The strnlen() function returns strlen(s), if that is less than maxlen, or maxlen if there is no null terminating  ('')  among	the  first
       maxlen characters pointed to by s.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute	  | Value   |
       +----------+---------------+---------+
       |strnlen() | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO

       POSIX.1-2008.

SEE ALSO

       strlen(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2016-03-15								STRNLEN(3)
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