Arguments

 

s1

   On the first call, a pointer to a string containing zero or more
   text tokens. On all subsequent calls for that string, a NULL
   pointer.
 

s2

   A pointer to a separator string consisting of one or more
   characters. The separator string may differ from call to call.
 

s

   A null-terminated string that is a sequence of zero or more text
   tokens separated by spans of one or more characters from the
   separator string sep.
 

sep

   A null-terminated string of separator characters. This separator
   string can be different from call to call.
 

lasts

   A pointer that points to a user-provided pointer to stored
   information needed for strtok_r to continue scanning the same
   string.