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Top Forums Programming pointer arithmetic vs. strlen() & strnlen()? Post 302280438 by Corona688 on Tuesday 27th of January 2009 12:07:15 AM
Old 01-27-2009
If he uses something other than NULLs to terminate strings, then he needs his own strlen. If he already has given lengths for data, he doesn't need strlen. But if he thinks writing his own will be faster than the library function that's not too likely. gcc in particular has intrinsics that can reduce it to a vanishingly small number of instructions in some cases and architectures.

He does have a point, though, in that sockets deliver raw data, not strings per-se. They only have nulls on the end if you send nulls, which is not something you want to rely on with data from an uncontrolled outside source. better to deal with data in random lengths than measure it every time.

Last edited by Corona688; 01-27-2009 at 01:13 AM..
 

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STRING(3)						     Library Functions Manual							 STRING(3)

NAME
strcat, strncat, strcmp, strncmp, strcasecmp, strncasecmp, strcpy, strncpy, strlen, index, rindex - string operations SYNOPSIS
#include <strings.h> char *strcat(s, append) char *s, *append; char *strncat(s, append, count) char *s, *append; int count; strcmp(s1, s2) char *s1, *s2; strncmp(s1, s2, count) char *s1, *s2; int count; strcasecmp(s1, s2) char *s1, *s2; strncasecmp(s1, s2, count) char *s1, *s2; int count; char *strcpy(to, from) char *to, *from; char *strncpy(to, from, count) char *to, *from; int count; strlen(s) char *s; char *index(s, c) char *s, c; char *rindex(s, c) char *s, c; DESCRIPTION
These functions operate on null-terminated strings. They do not check for overflow of any receiving string. Strcat appends a copy of string append to the end of string s. Strncat copies at most count characters. Both return a pointer to the null- terminated result. Strcmp compares its arguments and returns an integer greater than, equal to, or less than 0, according as s1 is lexicographically greater than, equal to, or less than s2. Strncmp makes the same comparison but looks at at most count characters. Strcasecmp and strncasecmp are identical in function, but are case insensitive. The returned lexicographic difference reflects a conversion to lower-case. Strcpy copies string from to to, stopping after the null character has been moved. Strncpy copies exactly count characters, appending nulls if from is less than count characters in length; the target may not be null-terminated if the length of from is count or more. Both return to. Strlen returns the number of non-null characters in s. Index (rindex) returns a pointer to the first (last) occurrence of character c in string s or zero if c does not occur in the string. Set- ting c to NULL works. 4th Berkeley Distribution October 22, 1987 STRING(3)
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