выделять слова можно функцией
Find the next token in a string.
char *strtok(
   char *strToken,
   const char *strDelimit 
);
Parameters
strToken  - String containing token or tokens. 
strDelimit -Set of delimiter characters. 
Returns a pointer to the next token found in strToken. They return NULL when
 no more tokens are found. Each call modifies strToken by substituting a
 NULL character for each delimiter that is encountered.
On the first call to strtok, the function skips leading delimiters and returns
 a pointer to the first token in strToken, terminating the token with a null
 character. More tokens can be broken out of the remainder of strToken by
 a series of calls to strtok. Each call to strtok modifies strToken by
 inserting a null character after the token returned by that call. To read
 the next token from strToken, call strtok with a NULL value for the
 strToken argument. The NULL strToken argument causes strtok to search for
 the next token in the modified strToken. The strDelimit argument can take
 any value from one call to the next so that the set of delimiters may vary.
Note   Each function uses a static variable for parsing the string into tokens.
 If multiple or simultaneous calls are made to the same function, a high
 potential for data corruption and inaccurate results exists. Therefore,
 do not attempt to call the same function simultaneously for different
 strings and be aware of calling one of these functions from within a loop
 where another routine may be called that uses the same function. However,
 calling this function simultaneously from multiple threads does not have
 undesirable effects.
из мсдн
// crt_strtok.c
/* In this program, a loop uses strtok
 * to print all the tokens (separated by commas
 * or blanks) in the string named "string".
 */
#include <string.h>
#include <stdio.h>
char string[] = "A string\tof ,,tokens\nand some  more tokens";
char seps[]   = " ,\t\n";
char *token;
int main( void )
{
   printf( "Tokens:\n" );
   /* Establish string and get the first token: */
   token = strtok( string, seps );
   while( token != NULL )
   {
      /* While there are tokens in "string" */
      printf( " %s\n", token );
      /* Get next token: */
      token = strtok( NULL, seps );
   }
}
Output
Tokens:
 A
 string
 of
 tokens
 and
 some
 more
 tokens