#include <stdio.h>
#include <ctype.h>
#include <string.h>
#define MAXWORD 80
#define NKEYS (sizeof(keytab) / sizeof(struct key))
struct key
{
char *word;
int count;
} keytab[] =
{
"auto", 0,
"break", 0,
"case", 0,
"char", 0,
"const", 0,
"continue", 0,
"default", 0,
"do", 0,
"double", 0,
"else", 0,
"enum", 0,
"extern", 0,
"float", 0,
"for", 0,
"goto", 0,
"if", 0,
"int", 0,
"long", 0,
"register", 0,
"return", 0,
"short", 0,
"singed", 0,
"sizeof", 0,
"static", 0,
"struct", 0,
"switch", 0,
"typedef", 0,
"union", 0,
"unsigned", 0,
"void", 0,
"volatile", 0,
"while", 0
} ;
void getword(char *, int);
int binsearch(char *, struct key *, int);
int main(int argc, char *argv[])
{
int n;
char word[MAXWORD];
printf("本程序将为您统计C语言的关键字的个数,请输入,输入end结束输入:
");
do
{
getword(word, MAXWORD);
if (isalpha(word[0]))
{
if ((n = binsearch(word, keytab, NKEYS)) >= 0)
{
keytab[n].count++; //找到则对应次数+1
}
}
}
while (strcmp(word, "end") != 0);
printf("您的输入中C语言关键字出现的次数统计如下:
");
for (n = 0; n < NKEYS; n++)
{
if (keytab[n].count > 0)
{
printf("%-10s: %6d
", keytab[n].word, keytab[n].count);
}
}
return 0;
}
/* 折半查找:在tab[0]到tab[n-1]中查找word */
int binsearch(char *word, struct key tab[], int n)
{
int result;
int low, high, mid;
low = 0;
high = n - 1;
while (low <= high)
{
mid = (low + high) / 2;
if ((result = strcmp(word, tab[mid].word)) < 0)
{
high = mid - 1;
}
else if (result > 0)
{
low = mid + 1;
}
else
{
return mid;
}
}
return -1;
}
/* getword:从输入中获取某个单词 */
void getword(char *word, int lim)
{
int c;
void ungetch(int);
char *w = word;
while (isspace(c = getchar()))
{
}
if (c != EOF)
{
*w = c;
w++;
}
if (!isalpha(c))
{
*w = '