用链表做通讯录的问题

C/C++ code

#include<stdio.h>#include<stdlib.h>#include<conio.h>#include<string.h>#include <malloc.h>#define NULL 0int length=0;struct student{    int num;     char name[10];    char birth[8];    char mov[15];    char fax[15];    char qnum[11];    char addr[50];    struct student *next;};void cover(){    printf("\n");    printf("\n");    printf("\n");    printf("\n");    printf("\t\t****************************************\n");    printf("\t\t********欢迎使用电子通讯录**************\n");    printf("\t\t****************************************\n");    printf("\n");    printf("\t\t\t1:添加信息\n");    printf("\t\t\t2:删除信息\n");    printf("\t\t\t3:修改信息\n");    printf("\t\t\t4:查询信息\n");    printf("\t\t\t5:显示所有信息\n");    printf("\t\t\t0:退出\n");    printf("\t\t\t请输入你的选择：\n");}void add(){        struct student *head,*q,*p;        while(p=(struct student *)malloc(sizeof(struct student)), printf("请输入学号:(学号为0时结束添加)\n"),scanf("%d",&p->num),p->num!=0)    {        if(length==0)        {             head=p;        }        else        {             q->next=p;        }        q=p;                 printf("请输入姓名:\n");        scanf("%s",p->name);        printf("请输入生日:\n");        scanf("%s",p->birth);        printf("请输入电话:\n");        scanf("%s",p->mov);        printf("请输入传真:\n");        scanf("%s",p->fax);        printf("请输入企鹅号:\n");        scanf("%s",p->qnum);        printf("请输入地址:\n");        scanf("%s",p->addr);        length++;    }    q->next=NULL;}void search(){    struct student *head,*q,*p;    int num;    int choice=1;    printf("请输入要查询的学号:\n");    scanf("%d",&num);             while(p=(struct student *)malloc(sizeof(struct student)),choice!=0)             {             if(length==0)          {             head=p;          }         else         {             q->next=p;         }         q=p;             if(num==p->num)             {                  printf("%d\n",p->num);                  printf("%s\n",p->name);                  printf("%s\n",p->birth);                  printf("%s\n",p->mov);                  printf("%s\n",p->fax);                  printf("%s\n",p->qnum);                  printf("%s\n",p->addr);                     choice=0;            }             length++;             }}       void show(){    struct student *head,*p;    for(p=head;p!=NULL;p=p->next)    {      printf("学号：");      printf("%d\n",p->num);      printf("姓名：");      printf("%s\n",p->name);      printf("生日：");      printf("%s\n",p->birth);      printf("电话：");      printf("%s\n",p->mov);      printf("传真：");      printf("%s\n",p->fax);      printf("企鹅号：");      printf("%s\n",p->qnum);           printf("地址：");      printf("%s\n",p->addr);    }}main(){       system("color 6b");    int choice;     //re();    while(1)    {      system("cls");           cover();      scanf("%d",&choice);      switch(choice)      {        case 1:add();//save();            break;        //case 2:del();//save();            //break;        //case 3:update();//save();            //break;        case 4:search();            break;        case 5:show();            break;        //case 0:quit();save();            //break;        default:        {            system("cls");            printf("选择错误，重新输入\n");            system("PAUSE");        }     }    }    } 
 

刚开始学链表，很多地方不懂，目前我做了添加，查找和显示全部。添加好像没问题
问题1：查找只要一输入学号就错误。
问题2：显示全部的时候是乱码。
这2个问题不知道怎么解决啊，我做了2个多小时都没搞定T.T

[解决办法]
太乱了.lz看看这个链接吧,虽然是管理系统的,但是和通讯录差不多,改个名字而已.
http://tieba.baidu.com/f?kz=1109535412
[解决办法]
学号后面跟上getchar();是不是把回车空格什么的也接受了?