[Not a question] swapping of words in a string

How about using strcspn and strlen:

...
char str[] = "...";     // your line to transform inplace
const char sep[] = " "; // you name the separators here, many more?
int len = 0;
char *word = str;
while(NULL != (word = next_word(sep, word, &len))) swap_wordchars(word, len)
printf("%s", str);

int next_word(char *sep, char *word, int *len)
{
   // move forward behind the last match
   word += *len;
   // get length until separator or until end of text (try until no leading sep)
   while(0 == (*len = strcspn(word, sep)) && *word) word++;
   // no more data: NULL
   return *len ? word : NULL;
}

void swap_wordchars(char* str, int len)
{
   int sentry = len / 2;
   for(int i = 0; i < sentry; ++i) swap_chars(str+i, str+len-1-i);
}

void swap_chars(char *a, char *b)
{
    char c = *a;
    *a = *b;
    *b = c;
}

I did now half of your homework - you have to do some boiler plate coding (add appropriate includes and the main function), compile, link, run.
And you might need to explain the code to someone ;-)

Cheers
Andi

visit here..

http://answers.yahoo.com/question/index?qid=20101213084823AA65Hpq[^]

It is solution for your question.

ROT13