c - Strtok not creating a token -

i trying parse char * array tokens , researching strtok. whenever run code, doesn't return temporary value , wondering doing wrong

int length; int = 0; int tokencounter = 0; int commandcounter = -1; char *temptoken;  char tempinput[max_line];  length = read(stdin_fileno, tempinput, max_line);  commandcounter = -1;  if (length < 0) {     perror ("there error reading command"); } else if (length == 0) {     exit (0); } else {     (i = 0; < length; ++i)     {         if (tempinput[i] == "\n" || tempinput[i] == ' ' || tempinput == "\t")         {             /*             if (commandcounter != -1)             {                 ptokens[tokencounter] = &tempinput[commandcounter];                 ++tokencounter;             }              tempinput [i] = '\0';             commandcounter = -1;             */         }         else         {             temptoken = strtok (tempinput, " \n");              while (temptoken != null)             {               strcpy(ptokens[tokencounter], temptoken);               temptoken = strtok (tempinput, " \n");             }             ++tokencounter;         }     } } ptokens[tokencounter] = null; 

temptoken = strtok (tempinput, " \n"); 

other first time null pointer has passed strtok, mean inside while loop, null has passed instead of string.

temptoken = strtok (null, " \n");