Strsep and Strtok_r Replacement strtok

Char *strtok (char *str, const char *delim)

The data source is modified. External lock is thread safe (strtok execution ends and unlocks another strtok loop knowing work is done)

The static external variable char*old in the Strtok implementation file is primarily accessed with mutexes. The source code is as follows.

#include <string.h>Static Char*olds;#undefStrtok/*Parse S into tokens separated by characters in DELIM.  If S is NULL and the last string Strtok () was called with is used.        For Example:char s[] = "-abc-=-def";             x = Strtok (S, "-");         x = "abc" x = Strtok (NULL, "-=");          x = "def" x = Strtok (NULL, "="); x = NULL//s = "abc\0=-def\0"*/Char*Strtok (S, Delim)Char*s; Const Char*Delim; {  Char*token; if(s = =NULL) s=olds; /*Scan leading delimiters. */s+=strspn (S, Delim); if(*s = =' /') {olds=s; returnNULL; }  /*Find The end of the token. */token=s; S=strpbrk (token, delim); if(s = =NULL)/*This token finishes the string. */Olds= __RAWMEMCHR (token,' /'); Else    {      /*Terminate the token and make OLDS point past it. */*s =' /'; Olds= S +1; }  returntoken;}

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Char *strsep (char **stringp, const char *delim)

The data source is modified. Reentrant, note that there is nothing to do with STRINGP's changes, mainly the static variables are not used.

#include <string.h>#undef__strsep#undefStrsepChar*__strsep (Char**STRINGP,Const Char*Delim) {  Char*begin, *end; Begin= *STRINGP; if(Begin = =NULL)returnNULL; /*A frequent case was when the delimiter string contains only one character.  Here we don ' t need to the expensive ' strpbrk ' function and instead work using ' STRCHR '. */  if(delim[0] ==' /'|| delim[1] ==' /')  {      CharCH = delim[0]; if(ch = =' /') End=NULL; Else        {            if(*begin = =ch) End=begin; Else if(*begin = =' /') End=NULL; ElseEnd= STRCHR (begin +1, CH); }  }  Else    /*Find The end of the token. */End=strpbrk (begin, Delim); if(end) {/*Terminate the token and set *STRINGP past NUL character. */*end++ =' /'; *STRINGP =end; }  Else    /*No more delimiters; */*STRINGP =NULL; returnbegin;}

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Note that the problem of empty strings occurs more than once because STRSEP handles more than one delimit character by returning an empty character string instead of NULL (see source), http://blog.csdn.net/striver1205/article/ details/25601885

Strsep even changed the pointer of the original string to point to ... This is not the other two functions. The Man manual mentions:

The Strsep () function is introduced as a replacement for strtok (3) and since the latter cannot handle empty fields.
However, Strtok (3) conforms to c89/c99 and hence are more portable.

Char *strtok_r (char *str, const char *delim, char **saveptr)

The data source is modified. Can be re-entered.

Strsep and Strtok_r Replacement strtok