result of strstr(cs,ct) when ct is a null string

[Erik Naggum]

Todd Karakashian writes:
|
|   Is the result of strstr(cs,ct) defined when ct is a null string
|   (i.e., when *ct == '\0')?
|
|   SunOS 4.1.1 strstr() returns cs in this situation.  I checked the man
|   page, K&R 2, and the ANSI standard but couldn't find any illuminating
|   information (like, for example, saying it was undefined).
|
|   I am thinking perhaps that strstr() ought to return NULL in this case, or
|   maybe a pointer to the null termination of cs, but I am curious what
|   other people think.

The null string matches any string, including the null string.

4.11.5.7 in dpANS C of 1/11/88 (which is the one I have handy -- time
to drag the ANSI standard with me in addition to so many other bulky
standards, it seems) clearly states:

	#include <string.h>
	char *strstr (const char *s1, const char *s2);

	...

	Returns

	    The strstr function returns a pointer to the located
	string, or a null pointer if the string is not found.  If s2
	points to a string with zero length, the function returns s1.

</Erik>
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Erik Naggum             Professional Programmer            +47-2-836-863
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