c - Can't find documentation for strtok_s() -

what each argument passed it, return?

how better regular strtok?

please give me simplified , basic explanation possible.

this detailed in appendix k (bounds checking interfaces) of iso c11 standard. optional part of standard provides "safer" ^(a) versions of existing functionality provided in core part of standard.

the prototype is:

char *strtok_s (     char * restrict        s1,     rsize_t * restrict     s1max,     const char * restrict  s2,     char ** restrict       ptr); 

the runtime constraints checked part of safety features are:

• the pointers s1max, s2, , ptr must non-null.
• if s1 null pointer, *ptr must not be.
• the value of *s1max must less or equal rsize_max.
• the end of token found must occur within first *s1max characters of s1 first call
• the end of token found must occur within first *s1max characters of searching resumes on subsequent calls.

the safety aspect that, if of constraints violated, no indirection occurs on s1 or s2 , no value stored via ptr.

other checks, pretty works identically standard strtok function, returning tokens s1 separated groups of delimiters found in s2. think use of ptr makes thread-safe since using non-static state provided user ^(b).

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^(a) quoted because parts of standard already safe if know how use them :-)

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^(b) 1 thing that's still missing ability have empty tokens such as:

field1||||field5 

because strtok_s (and original) treat |||| single separator, have find other ways </rant> :-)