如何在此程序中添加上输出全部数据的函数

#include "stdio.h"

#include "stdlib.h"

#include "string.h"

/*定义学生结构体*/

struct Student

{

 char ID[20];  

 char Name[20];  

 char phone[20];  

 char address[20];  

 char QQ[20];    

};

/*声明学生数组及学生数量*/

struct Student students[1000];

int num=1000;

/*通过学号返回数组下标*/

int Student_SearchByIndex(char id[])

{

int i;

for (i=0;i<num;i++)

{

if (strcmp(students[i].ID,id)==0)

{

return i;

}

}

return -1;

}

/*通过姓名返回数组下标*/

int Student_SearchByName(char name[])

{

int i;

for (i=0;i<num;i++)

{

if (strcmp(students[i].Name,name)==0)

{

return i;

}

}

return -1;

}

/*显示单条学生记录*/

void Student_DisplaySingle(int index)

{

printf("%15s%15s%15s%15s%15s\n","学号","姓名","电话","住址","QQ");

printf("------------------------------------------------------------------------------\n");

printf("%10s%15s%20s%15s%12s\n",students[index].ID,students[index].Name,

students[index].phone,students[index].address,students[index].QQ);

}

/*插入学生信息*/

void Student_Insert()

{

while(1)

{

printf("请输入学号:");

scanf("%s",&students[num].ID);

getchar();

printf("请输入姓名:");

scanf("%s",&students[num].Name);

getchar();

printf("请输入电话:");

scanf("%s",&students[num].phone);

getchar();

printf("请输入住址:");

scanf("%s",&students[num].address);

getchar();

printf("请输入QQ:");

scanf("%s",&students[num].QQ);

getchar();

num++;

printf("是否继续?(y/n)");

if (getchar()=='n')

{

break;

}

}

}

/*修改学生信息*/

void Student_Modify()

{

while(1)

{

char id[20];

int index;

printf("请输入要修改的学生的学号:");

scanf("%s",&id);

getchar();

index=Student_SearchByIndex(id);

if (index==-1)

{

printf("学生不存在!\n");

}

else

{

printf("你要修改的学生信息为:\n");

Student_DisplaySingle(index);

printf("-- 请输入新值--\n");

printf("请输入学号:");

scanf("%s",&students[index].ID);

getchar();

printf("请输入姓名:");

scanf("%s",&students[index].Name);

getchar();

printf("请输入电话:");

scanf("%f",&students[index].phone);

getchar();

printf("请输入住址:");

scanf("%f",&students[index].address);

getchar();

printf("请输入QQ:");

scanf("%f",&students[index].QQ);

getchar();

}

printf("是否继续?(y/n)");

if (getchar()=='n')

{

break;

}

}

}

/*删除学生信息*/

void Student_Delete()

{

int i;

while(1)

{

char id[20];

int index;

printf("请输入要删除的学生的学号:");

scanf("%s",&id);

getchar();

index=Student_SearchByIndex(id);

if (index==-1)

{

printf("学生不存在!\n");

}

else

{

printf("你要删除的学生信息为:\n");

Student_DisplaySingle(index);

printf("是否真的要删除?(y/n)");

if (getchar()=='y')

{

for (i=index;i<num-1;i++)

{

students[i]=students[i+1];//把后边的对象都向前移动

}

num--;

}

getchar();

}

printf("是否继续?(y/n)");

if (getchar()=='n')

{

break;

}

}

}

/*按姓名查询*/

void Student_Select()
{

while(1)

{

char name[20];

int index;

printf("请输入要查询的学生的姓名:");

scanf("%s",&name);

getchar();

index=Student_SearchByName(name);

if (index==-1)

{

printf("学生不存在!\n");

}

else

{

printf("你要查询的学生信息为:\n");

Student_DisplaySingle(index);

}

printf("是否继续?(y/n)");

if (getchar()=='n')

{

break;

}

}

}

/*显示学生信息*/

void Student_Display()

{

int index;
int i;

printf("%10s%10s%10s%10s%10s\n","学号","姓名","电话","住址","QQ");

printf("--------------------------------------------------------------------------------\n");

for (i=0;i<num;i++)

{

printf("%10s%15s%20s%15s%12s\n",students[index].ID,students[index].Name,

students[index].phone,students[index].address,students[index].QQ);
}

}

/*将学生信息从文件读出*/

void IO_ReadInfo()

{

FILE *fp;

int i;

if ((fp=fopen("Database.txt","rb"))==NULL)

{

printf("不能打开文件!\n");

return;

}

if (fread(&num,sizeof(int),1,fp)!=1)

{

num=-1;

}

else

{

for(i=0;i<num;i++)

{

fread(&students[i],sizeof(struct Student),1,fp);

}

}

fclose(fp);

}

/*将学生信息写入文件*/

void IO_WriteInfo()

{

FILE *fp;

int i;

if ((fp=fopen("Database.txt","wb"))==NULL)

{

printf("不能打开文件!\n");

return;

}

if (fwrite(&num,sizeof(int),1,fp)!=1)

{

printf("写入文件错误!\n");

}

for (i=0;i<num;i++)

{

if (fwrite(&students[i],sizeof(struct Student),1,fp)!=1)

{

printf("写入文件错误!\n");

}

}

fclose(fp);

}

/*主程序*/

void main()

{

int choice;

IO_ReadInfo();

while(1)

{

     /*主菜单*/ 
     printf("\n*************************************************\n");
     printf("\n*********   学生通讯录管理系统          *********\n");  
     printf("\n*********    1. 增加学生记录            *********\n");  
     printf("\n*********    2. 修改学生记录            *********\n");  
     printf("\n*********    3. 删除学生记录            *********\n");  
     printf("\n*********    4. 按姓名查询学生记录      *********\n");
     printf("\n*********    5. 退出                    *********\n"); 
     printf("\n*************************************************\n"); 
     printf("请选择(1-5):");    
     scanf("%d",&choice);    
     getchar();    
     switch(choice)  
     {  
     case 1:  
          Student_Insert();  
          break;  
     case 2:  
          Student_Modify();  
          break;  
     case 3:  
          Student_Delete();  
          break;  
     case 4:  
          Student_Select(); 
         break; 
     case 5:  
          exit(0);  
          break;  
     }  
     IO_WriteInfo();  
 }   

}

代码太多太乱。你先要模块化你的程序。