C 語言統計關鍵字出現次數

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

#define NKEYS (sizeof keytab / sizeof(struct key))

struct key 
{
char *word;
int count;
};

/*關鍵字列表(注意一定要按字典排序)*/
struct key keytab[15] = 
{
  "abort",0,
   "break",0,
   "clock",0,
   "define",0,
   "echo",0,
   "fgetc",0,
   "get",0,
   "help",0,
   "insert",0,
   "jump",0,
   "kind",0,
   "long",0,
   "malloc",0,
   "null",0,
   "operate",0

};

int binarysearch(char *word, struct key tab[], int n);
int getword(char *word);


/*<The C programming language (second edition) 中的小練習>

  功能：統計輸入文本中關鍵字出現的次數。
*/
int main()
{
  char word[30];
  int n;

  while(getword(word) != 0 && strcmp(word,"quit") != 0)
  {
    if((n = binarysearch(word,keytab,NKEYS )) >= 0);
	   keytab[n].count++;
  }
  for(n = 0; n < NKEYS; n++)
  {
    if(keytab[n].count > 0)
		printf("%s  :  %d\n",keytab[n].word,keytab[n].count);
  }
 
  return 0;
}

/*從輸入端得到一個單詞*/
int getword(char *word)
{ char c;
  int i = 0;

  while(isspace(c = getchar()))
	  ;
  while(1)
  {
	  if(c != '\n' && c != ' ' && c != '\t' && isalpha(c))
	     word[i++] = c;
	  if(c == '\n' || c == ' ' )
	  {   
		  word[i] = '\0';
		  
		  return i;
	  }
	  c = getchar();
  } 
  return i;
}

/*binarysearch 函數： 在tab[0]到tab[n]中查找單詞*/
int binarysearch(char *word, struct key tab[], int n)
{
  int mid,l,h,flag;
  l= 0;
  h = n - 1;

  while(l <= h)
  {
    mid = (l + h)/2;
	if( (flag = strcmp(word,tab[mid].word)) < 0)
		h = mid - 1;
	else if(flag > 0)
		l = mid + 1;
	else
		return mid;
  
  
  }
     
  return -1;
}