# include <stdio.h>
# include <stdlib.h>
#include<ctype.h>
# include <string.h>
# define N 100
int S1=0,S2=0,S3=0,man=0,woman=0,pl=0,g=0;//定义s为诊室，p1指针
int k;
struct hos
{
    char name[15]; //患者姓名
    char sex[10]; //患者性别
    char num[10]; //挂号单编号
    char year[10]; //患者年龄
   int  room; //被分到的诊室号
};
struct hos h[N];
struct hos *p=&h[0];
void introduce() //功能介绍introduce()函数
{
printf("                     \n◎ 功 能 选 择 ◎                  \n");
printf("-----------------------------------------------------------\n");
printf("|  ●1-挂号                                                 |\n");
printf("| ●2-叫号                                                 |\n");
printf("|●3-分诊室                                               |\n");
printf("|●4-显示各诊室队列信息                                   |\n");
printf("|●5-统计当天就诊患者情况(要求按性别和任意年龄区段进行统计|\n");
printf("|●6-结束程序                                             |\n");
printf("---------------------------------------------------------\n");
}
void run()
{
    void introduce();
    void input ();
    void jiaohao();
    void fp();
    void statistic();
    void type_statistic();
    char function='1',j[10];
    while (function)
    {
        switch(function)
        {
        case'1':input();break;
        case'2':jiaohao();break;
        case'3':fp();break;
        case'4':statistic();break;
        case'5':type_statistic();break;
        case'6':exit(0);break;
        default:system("cls"); //清屏
        printf("\n\terror\n\n 请重新输入:");
        }
        printf("请选择功能");
        introduce();
        function=getchar();
        gets(j);
             while(isdigit(function)==0) //isdigit(function):判断function字符是不是数字
        {
            printf("您输入有误,请重新输入");
            function=getchar();
            gets(j);   
        }
    }
}

void input()
{
    int change(char);
// int d;
    char i,j[8],s[15];
    printf("请输入需要挂号的病人人数(请输入0到9之间的数):");
    i=getchar();
    gets(j);
        while(isdigit(i)==0)                         //isdigit(i):判断i字符是不是数字
        {
            printf("您输入有误，请重新输入");
            i=getchar();
            gets(j);
        }
            printf("请输入%d位病人的个人信息\n",change(i));
            for(k=1;k<=change(i);k++)
           {  
               printf("第%2d位病人:\n",k);
                printf("姓名 :");strcpy(p[pl].name,gets(s));
                printf("编号 :");
                strcpy(p[pl].num,gets(s));
           /* for(d=pl;d>=0;d--)
           {
                if(p[pl].num==p[d].num&&pl!=d)
                 printf("error");
             }*/
          printf("性别 :");
            strcpy(p[pl].sex,gets(s));
            printf("年龄 :");
            strcpy(p[pl].year,gets(s));
            pl++;
            }

            printf("已经挂号的病人\n");
            
            for(k=g;k<pl;k++)
               printf("第%2d 位 姓名:%s        挂号号码%s\n",k+1-g,p[k].name,p[k].num);

          system("pause");//暂停
            system("cls"); //清屏
}
void jiaohao()
{
   if(g==pl)
         {
         system("cls");
         printf("所有病人都已经分配完毕\n");
         return ;
         }
printf("病人%s已前往就诊挂号号码:%5s\n\n",p[g].name,p[g].num);
         g++;
         printf("剩余%2d 位等待叫号的病人\n",pl-g);
         for(k=g;k<pl;k++)
printf("挂号排序第%2d 位  姓名:%s  挂号号码:   %5s\n",k+1-g,p[k].name,p[k].num);
system("pause");
system("cls");
}
void fp()                             //分配诊室:fp()函数
{
S1=0;S2=0;S3=0;
for(k=0;k<g;k++)
        {
           if(atoi(p[k].year)>=35)
           {
S1++;
p[k].room=1;
            }                        //其中35(含35)岁以上的患者在第一诊室
          else
                if(strcmp(p[k].sex,"man")==0)
               {
                     S2++;
                     p[k].room=2;
               }                    //35岁以下男患者进第二诊室
               else
               {     S3++;
                     p[k].room=3;
                }                  //其它的患者进第三诊室
printf("病人%s被分配在第%d诊室\n",
p[k].name,p[k].room,p[k].num);
        }
        system("pause");
        system("cls");
}
void statistic()                  //病人信息输出:statistic()函数
{
     for(k=0;k<g;k++)
          {
            printf(" 第%2名患者姓名:%s    挂号编号:%s      诊室:第% d诊室\n",k+1,p[k].name,p[k].num,p[k].room);
}
          printf("第一诊室%2d人\n",S1);
            printf("第二诊室%2d人\n",S2);
            printf("第三诊室%2d人\n",S3);
        system("pause");
        system("cls");
}
void type_statistic()             //统计功能:type_statistic()函数
{
int year,high=0,low=0;man=0;woman=0;
    for(k=0;k<g;k++)
         {
if(strcmp(p[k].sex,"man")==0)man++;
else woman++;
}
printf("请输入一个界限年龄:");
scanf("%d",&year);
         
for(k=0;k<g;k++)
       {
if(atoi(p[k].year)>=year)high++;
else low++;
         }
printf("共有%2d位患者就诊.\n",g);
printf("其中男性患者有%2d位",man);
printf("女性患者有%2d位.\n",woman);
printf("年纪大于等于%d的患者有%2d位,",year,high);
printf("年纪小于%d的患者有%2d位.\n",year,low);
system("pause");
system("cls");
}

void main()
{
system("color 70");
introduce();
run();
}
int change(char ch)
//将单个字符型数字转化为整形
     {
int i;
i=ch-48;
return(i);
     }

程序应该是对的吧！

供参考：

void write_file()
{
    int i = 0;
    FILE* fp;
    fp = fopen("hos_data.txt", "w");
    if (fp == NULL) return;
    while (i < pl) {
        fprintf(fp, "%s %s %s %s %d\n", h[i].name, h[i].sex, 
                               h[i].num, h[i].year, h[i].room);
        i++;
    }
    fclose(fp);
}