/*---------------------------------------------------------------------------
File name: ReverseWords.c
Author: HJin (email: fish_sea_bird [at] yahoo [dot] com )
Created on: 7/25/2007 09:05:10
Environment: Windows XP Professional SP2 English +
Visual Studio 2005 v8.0.50727.762

Modification history:
===========================================================================

1. I wrote this function a few years ago. Fully test it before delivering it
to your client.
2. I removed comments to force you study the code instead of copy it.
3. Good luck!
*/

#include <stdio.h>
#include <string.h>

void strsrev(char* p, char* r)
{
char t;
while(p<r)
{
t = *p;
*p++ = *r;
*r-- = t;
}
}

/**
Reverse words in place.

O(n) algorithm.
*/
void wordrev(char* s)
{
char*b =s, *e = s+strlen(s)-1;

if(!s)
return;

strsrev(b, e);
b=e=s;

while(*b)
{
while(*b && *b == ' ')
++b;

e = b;
while(*e && *e != ' ')
++e;

strsrev(b, e-1);

b=e;
}
}

int main()
{
char s[100] = "Somewhere i belong.";

wordrev(s);
*s &= 0xDF;

printf("%s\n", s);

return 0;
}