Code#83:c program remove spaces, blanks from a string using pointers

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define SPACE ' '

main()
{
   char string[100], *blank, *start;
   int length, c = 0, d = 0;

   printf("Enter a string\n");
   gets(string);

   length = strlen(string);

   blank = string;

   start = (char*)malloc(length+1);

   if ( start == NULL )
      exit(EXIT_FAILURE);

   while(*(blank+c))
   {
      if ( *(blank+c) == SPACE && *(blank+c+1) == SPACE )
      {}
      else
      {
         *(start+d) = *(blank+c);
     d++;
      }
      c++;
   }
   *(start+d)='\0';

   printf("%s\n", start);

   free(start);    

   return 0;
}