dataStructure/keytab.c at master · taohi/dataStructure · GitHub

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

#define MAXWORD 100
#define NKEYS (sizeof keytab / sizeof keytab[0])

struct key {
    char *word;
    int count;
}keytab[]={
    "auto",0,
    "break",0,
    "case",0,
    "char",0,
    "const",0,
    "continue",0,
    "default",0,
    "for",0,
    "struct",0,
    "unsigned",0,
    "void",0,
    "volatile",0,
    "while",0,
};

int getword(char *,int);
int binsearch(char *,struct key *,int);

main()
{
    int n;
    char word[MAXWORD];
    while (getword(word,MAXWORD)!=EOF)
        if(isalpha(word[0]))
            if((n=binsearch(word,keytab,NKEYS))>=0)
                keytab[n].count++;
    for(n = 0; n < NKEYS; n++)
        if(keytab[n].count >0)
            printf("%4d %s\n",keytab[n].count,keytab[n].word);
    return 0;
}

int binsearch(char *word,struct key tab[],int n)
{
    int cond;
    int low,high,mid;

    low=0;
    high=n-1;
    while(low <=high)
    {
        mid = (low + high)/2;
        if((cond = strcmp(word,tab[mid].word))<0)
            high = mid -1;
        else if(cond >0)
            low = mid +1;
        else
            return mid;
    }
    return -1;
}

int getword(char *word,int lim)
{
    char *w = word;
    int c;
    while(isspace (c = getchar()))
        ;
    if(c!=EOF)
        *w++ = c;
    if(!isalpha(c))
    {
        *w = '\0';
        return c;
    }
    for(;--lim>0;w++)
        if(!isalnum(*w = getchar()))
        {
            //ungetc(w);
            *w = '\0';
            break;
        }
    *w = '\0';
    return word[0];
}