c语言，功能简单的电话簿，实现输入，显示，查找的功能

感谢论坛里给我提供建议和意见的人，是你们的陪伴让我在风雨中前行，谢谢你们

特别感谢@NeilHappy  ,@codesnail   ,@xiakan008 ，你们对程序的完善提供的建设性的指导意见

c代码如下：

#include<stdio.h>#include<stdlib.h>#include<string.h>#define LEN sizeof(struct mystr)void main(){    struct mystr    {        char name[40];        char add[100];        char code[20];        char tel[20];        struct mystr *next;    };    FILE *fp;    struct mystr *head,*p1,*p2;    char select,useless,search_name[40];    int out_err_flag=0,search_flag=0;    if((fp=fopen("phonebook.txt","ab+"))==NULL)        {printf("File open error!\n");exit(0);}    /*SELECT MENU*/    printf("1.Insert a new record\n2.Display existed records\n");    printf("3.Search a record\nELSE Quit\nPlease give your choice:");    scanf("%c%c",&select,&useless);    /*select is 1, insert a new record*/    if(select=='1')    {        printf("NOTE: Use # to finish input\n");        p1=p2=(struct mystr *)malloc(LEN);        head=p1;        head->next=NULL;        do        {            printf("Input the name:");            gets(p1->name);            if(strcmp(p1->name,"#")==0)    break;            printf("Input the address:");            gets(p1->add);            if(strcmp(p1->add,"#")==0)    break;            printf("Input the post code:");            gets(p1->code);            if(strcmp(p1->code,"#")==0)    break;            printf("Input the telphone number:");            gets(p1->tel);            if(strcmp(p1->tel,"#")==0)    break;             /*write to phonebook.txt*/            if(fwrite(p1,LEN,1,fp)==0)    out_err_flag=1;            p1=(struct mystr *)malloc(LEN);            p2->next=p1;            p2=p1;        }while(1);        printf("With a '#', you have ended the input\n");        if(out_err_flag==1)            printf("Errors ocure when writing to file!\n");    }    /*select is 2, display existed records*/    else if(select=='2')    {        printf("NAME\tADD\tCODE\tTEL\n");        p1=(struct mystr *)malloc(LEN);        while(!feof(fp))        {            if(fread(p1,LEN,1,fp))                printf("%s\t%s\t%s\t%s\n",p1->name,p1->add,p1->code,p1->tel);        }        free(p1);    }    /*select is 3, do research*/    else if(select=='3')    {        printf("Support search by name, please give a name:");        gets(search_name);        p1=(struct mystr *)malloc(LEN);        while(!feof(fp))        {            if(fread(p1,LEN,1,fp))                if(strcmp(p1->name,search_name)==0)                {                    printf("NAME\tADD\tCODE\tTEL\n");                    printf("%s\t%s\t%s\t%s\n",p1->name,p1->add,p1->code,p1->tel);                    search_flag=1;                }        }        if(search_flag!=1)            printf("Nothing matched!\n");        free(p1);    }    /*if select is anything else, quit*/    else    exit(0);    fclose(fp);    getch();}