统计C语言关键字出现次数
《C程序设计语言》K&R版本第6章结构6.3结构数组内容
/*
Name: 统计c语言关键字出现次数
Copyright:
Author: lingr7
Date: 21/10/18 10:05
Description: 完全根据《C程序设计语言》K&R版本6.3结构数组内容编写。在dev c++5.11中编译运行成功
一个项目文件.dev,内含calc.h,getch.c,getop.c,keytab.h,tongjimain.c.4个子文件
关键字结构数组在keytab.h中定义，可以自行修改该表，但要注意，这个数组里顺序必须是字典序升序。
*/
/*tongjimain.c*/
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include "calc.h"
#include "keytab.h"
#define MAXWORD 100
int getword(char *, int);
int binsearch(char *, struct key *, int);
/*统计输入中c语言关键字的出现次数*/
main(){
int n;
char word[MAXWORD];
printf("%s %s %s", keytab[0].word, keytab[1].word, keytab[2].word);
while (getword(word,MAXWORD) != EOF)/*因为EOF而不易调试*/
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;
}
/*折半查找*/
/*2018年10月20日
lingr7*/
/* binsearch函数 ：在tab[0]到tab[n-1]中查找单词 */
int binsearch(char *word, struct key tab[], int n){
int cond;
int low, high, mid;
low = 0;
high = n - 1;
while (low <= high){
mid = (high+low) / 2;
if ((cond = strcmp(word, tab[mid].word)) < 0)
high = mid - 1;
else if (cond > 0)
low = mid + 1;
else /*找到了匹配的值*/
return mid;
}
return -1; /*没有匹配的值*/
}
/* getword函数：从输入中读取下一个单词或字符*/
int getword(char *word, int lim){
int c, getch(void);
void ungetch(int);
char *w = word;
while (isspace(c = getch()))
;
if (c != EOF)
*w++ = c;
if (!isalpha(c)) {
*w = '\0';
return c;
}
for ( ; --lim > 0; w++)
if (!isalnum(*w = getch())){
ungetch(*w);/**/
break;
}
*w = '\0';
return word[0];
}
/*calc.h*/
#define NUMBER '0'
/*void push(double);*/
/*double pop(void);*/
int getop(char []);
int getch(void);
void ungetch(int);
/*keytab.h*/
#define NKEYS ( sizeof keytab / sizeof(struct key))
/*结构初始化*/
/*最好声明为外部变量*/
struct key {
char *word;
int count;
} keytab[] ={
"auto", 0,
"break", 0,
"case", 0,
"char", 0,
"const", 0,
"continue", 0,
"default", 0,
"main", 0,
"unsigned", 0,
"void", 0,
"volatile", 0,
"while", 0,
};
/*getch.c*/
#include <stdio.h>
#define BUFSIZE 100
char buf[BUFSIZE]; /* buffer for ungetch */
int bufp = 0; /* next free position in buf */
int getch(void) /* get a (possibly pushed-back) character */
{
return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c) /* push character back on input */
{
if (bufp >= BUFSIZE)
printf("ungetch: too many characters\n");
else
buf[bufp++] = c;
}
/*getop.c*/
#include <stdio.h>
#include <ctype.h>
#include "calc.h"
/* getop: get next character or numeric operand */
int getop(char s[])
{
int i, c;
while ((s[0] = c = getch()) == ' ' || c == '\t')
;
s[1] = '\0';
if (!isdigit(c) && c != '.')
return c; /* not a number */
i = 0;
if (isdigit(c)) /* collect integer part */
while (isdigit(s[++i] = c = getch()))
;
if (c == '.') /* collect fraction part */
while (isdigit(s[++i] = c = getch()))
;
s[i] = '\0';
if (c != EOF)
ungetch(c);
return NUMBER;
}