分享：哈希表运用（宏定义）
功能:宏定义和宏定义删除终于把结构体这章弄完了，太耗时了。不过，这章和数组及指针那章学到的东西很多，不愧是金典！！！
Hashtab_Def.h:
程序代码：#ifndef HASHTAB_DEFINE
#define HASHTAB_DEFINE
#define MAXWORD 100
#define HASHSIZE 101
typedef struct Hlist
{
char *name;
char *def;
struct Hlist *next;
}HList;
Hlist *install(char *, char *);
Hlist *lookup(char *);
void error(int, char *);
int getch(void);
void ungetch(int);
int getword(char *, int);
void skipblanks(void);
void getdef(void);
void undef(char *);
void ungets(char *);
unsigned hash(char *s);
char *strdup(char *s);
static Hlist *hashtab[HASHSIZE];
#endif
Hashtab_Def.cpp:
程序代码：#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include "Hashtab_Def.h"
int main()
{
char w[MAXWORD];
int i;
Hlist *p;
while (getword(w, MAXWORD) != EOF)
if (strcmp(w, "#") == 0)
getdef();
else
printf("%s :not is define name\n", w);
printf("Please end EOF to printf result\n");
for (i = 0; i < HASHSIZE; i++)
for (p = hashtab[i]; p != NULL; p = p->next)
printf("%s %s\n", p->name, p->def);
return 0;
}
void getdef(void)
{
int c, i;
char name[MAXWORD], def[MAXWORD], dir[MAXWORD];
skipblanks();
if (!isalpha(getword(dir, MAXWORD)))
error(dir[0], "getdef :non-alpha - name expected");
else if (strcmp(dir, "define") == 0)
{
skipblanks();
if (!isalpha(getword(name, MAXWORD)))
error(name[0], "getdef: non -alpha -name expected");
else
{
skipblanks();
for (i = 0; i < MAXWORD; i++)
if ((def[i] = getch()) == EOF || def[i] == '\n')
break;
c = def[i];
def[i] = '\0';
if (c == '\n' && i == 0)
error('\n', "define cannot is line feed\n");
else
install(name, def);
}
}
else if (strcmp(dir, "undef") == 0)
{
skipblanks();
if (!isalpha(getword(name, MAXWORD)))
error(name[0], "getdef :non-alpha in undef");
else
undef(name);
}
else
error(dir[0], "error : not is #define or #undef");
}
void skipblanks()
{
int c;
while ((c = getch()) == '\t' || c == ' ')
;
ungetch(c);
}
void error(int c, char *s)
{
printf("error:%s\n", s);
while (c != EOF && c != '\n')
c = getchar();
}
Hlist *install(char *name, char *def)
{
Hlist *p;
unsigned hashval;
if ((p = lookup(name)) == NULL)
{
p = (Hlist *)malloc(sizeof(Hlist));
if (p == NULL || (p->name = strdup(name)) == NULL)
return NULL;
hashval = hash(name);
p->next = hashtab[hashval];
hashtab[hashval] = p;
printf("define successed\n");
}
else
free(p->def);
if ((p->def = strdup(def)) == NULL)
{
printf("redefine successed\n");
return NULL;
}
return p;
}
Hlist *lookup(char *s)
{
Hlist *p;
for (p = hashtab[hash(s)]; p != NULL; p = p->next)
if (!strcmp(s, p->name))
return p;
return NULL;
}
unsigned hash(char *s)
{
unsigned hashval;
for (hashval = 0; *s != '\0'; s++)
hashval = *s + 31 * hashval;
return hashval % HASHSIZE;
}
void undef(char *s)
{
int h;
Hlist *prev, *p;
prev = NULL;
h = hash(s);
for (p = hashtab[h]; p != NULL; p = p->next)
{
if (!strcmp(s, p->name))
break;
prev = p;
}
if (p != NULL) {
if (prev == NULL)
hashtab[h] = p->next;
else
prev->next = p->next;
free(p->name);
free(p->def);
free(p);
printf("Undef successed\n");
}
}GetWord.cpp:
程序代码：#include <ctype.h>
#include <stdio.h>
int getword(char *word, int lim)
{
int c, getch();
void ungetch(int);
char *w = word;
while (isspace(c = getch()))
;
if (c != EOF)
*w++ = c;
if (!isalnum(c)) {
*w = '\0';
return c;
}
for (; --lim; w++)
if (!isalnum(*w = getch()))
{
ungetch(*w);
break;
}
*w = '\0';
return word[0];
}Getch.cpp:
程序代码：#include<string.h>
#include <stdio.h>
#define BUFSIZE 100
char buf[BUFSIZE];
int bufp = 0;
int getch()
{
return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c)
{
if (bufp >= BUFSIZE)
printf("ungetch: too many charaters\n");
else
buf[bufp++] = c;
}
void ungets(char *s)
{
int len;
extern void ungetch(int);
while ((len = strlen(s)) > 0)
ungetch(s[--len]);
}
Strdup.cpp:
程序代码：#include <malloc.h>
#include <string.h>
char *strdup(char *s)
{
char *p;
p = (char *)malloc(strlen(s) + 1);
if (p != NULL)
strcpy(p, s);
return p;
}
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