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<A href="http://www.goodprogrammer.org/" target="blank">ios培训</A>

------我的c语言笔记，期待与您交流! 

#include<stdio.h>

#include<string.h>

#include<stdlib.h>

#define HASHSIZE 101

struct nlist

{

    struct nlist *next;

    char *name;

    char *defn;

};

/*hash函数：为字符串s生成散列值 p126*/

unsigned hash(char *s)

{

    unsigned hashval;

    for(hashval=0;*s!='\0';s++)

    hashval=*s+31*hashval;

    return hashval %HASHSIZE;

}

/*lookup函数：在hashtab中查找s  p126*/

struct nlist *lookup(char *s)

{

    struct nlist *np;

    for(np=hashtab[hash(s)];np!=NULL;np=np->next)

    if(strcmp(s,np->name)==0)

    return np;

    return NULL;

}

/*strdup函数：复制s到某个位置,并且把该地址返回 P126*/

char *strdup(char *s)

{

    char *p;

    p=(char *) malloc(strlen(s)+1);

    if(p!=NULL)

    strcpy(p,s);

    return p;

}

/*install函数：将（name,defn）加入到hashtab中 p127*/

struct nlist *install(char *name,char *defn)

{

    struct nlist *np;

    unsigned hashval;

    if((np=lookup(name))==NULL)

    {

        np=(struct nlist *) malloc(sizeof(*np));

        if(np==NULL||(np->name=strdup(name))==NULL)

        return NULL;

        hashval=hash(name);

        np->next=hashtab[hashval];//出现冲突的话，把新的np放在表头

        hashtab[hashval]=np;

    }

   else

        free((void *)np->defn);

   if((np->defn=strdup(defn))==NULL)

       return NULL;

   return np;

}

int main()

{

   char *s0="abcdefghijk";

   char *s1="1234";

   struct nlist *p,*p2;

   p=install(s0,s1);

   p2=install(s0,s1);

   printf("%s %s\n",p->name,p->defn);

   printf("%s %s\n",p2->name,p2->defn);

}