下面是根据班级，这个人数较少的单位设计的学籍管理系统，录入时，要求班内序号由1开始  按顺序录入，其中主要用到了 结构体数组，文件处理，循环语句，选择语句等方面的知识

在设计中遇到一个问题就是  不知道怎样修改已经保存在文件中的某一个指定学生的信息，后来在询问学长之后才了解到  可以： 先把文件中的数据全部读入结构体数组中，再修改指定序号的数组元素，然后再用“wt”的方式写进原文件，这样就可以删除文件里的原内容，再写进新内容

下面是源代码，在Dev-C++ 条件下进行编译

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<stdlib.h>
int count1=0;
int count2=0;
int count3=0;
void class_print();
void men1_student();
void men2_student();
void men3_student();
void men4_student();
void input_student();
void input_grade();
void input_reward();
void input_finance();
void report_finance();
void seek_student();
void seek_grade();
void seek_reward();
void change_student();
void change_grade();
void change_reward();
int now1_student();
int now2_student();
int now3_student();
struct date
{int year;int month;int day;
};
struct student
{char number[2];char name[10];char sex[4];char tel[15];char id[20];char study[10];
};
struct grade
{char number[2];char name[10];char math[4];char English[4];char Cprogram[4];char sumtest[4];
};
struct reward
{char number[2];char name[10];struct date time;char rewarding[80];
};
struct finance
{char thing[20];char type[8];struct date time2;int i;
};
struct student m_stu[50];
struct grade g_stu[50];
struct reward r_stu[50];
struct finance f_class;
struct grade t_change;
main()
{int choice=-1;                                                 //一级菜单 while(choice!=0){printf("\n");printf("\t\t\t\t\t\t**");  class_print();  printf("**\n");    printf("\t\t\t\t\t\t****************************\n");printf("\t\t\t\t\t\t**  班级学生学籍管理系统  **\n");printf("\t\t\t\t\t\t**     1.户籍管理系统     **\n");printf("\t\t\t\t\t\t**     2.成绩管理系统     **\n");printf("\t\t\t\t\t\t**     3.奖惩管理系统     **\n");printf("\t\t\t\t\t\t**     4.财务管理系统     **\n");printf("\t\t\t\t\t\t**     0.退        出     **\n");printf("\t\t\t\t\t\t请选择");scanf("%d",&choice);switch(choice){ case 1:men1_student();break;case 2:men2_student(); break;case 3: men3_student();break;case 4: men4_student();break;case 0:printf("返回上一级");break; default :break;}}
}
void men1_student()                                                                              //二级菜单（学生户籍管理）
{
int choice=-1;
while(choice!=0){printf("\n");printf("\t\t\t\t\t\t****************************\n");printf("\t\t\t\t\t\t**");  class_print();  printf("**\n");printf("\t\t\t\t\t\t**  班级学生户籍信息管理  **\n");printf("\t\t\t\t\t\t**  户籍信息已录入人数:");now1_student();printf("  **\n");printf("\t\t\t\t\t\t**     1.户籍录入系统     **\n");printf("\t\t\t\t\t\t**     2.户籍修改系统     **\n");printf("\t\t\t\t\t\t**     3.户籍查询系统     **\n");printf("\t\t\t\t\t\t**     0.返        回     **\n");printf("\t\t\t\t\t\t请选择"); scanf("%d",&choice);  switch(choice){case 1:input_student();break;case 2:change_student();break;case 3:seek_student();break;case 0:printf("返回上一级");break;default :break;}getch();}
}void input_student()                                                                                   // 户籍录入函数  录入信息保存至D盘根目录下information1.txt文件下{int j;printf("学生户籍信息录入");printf("\n班内序号: ");scanf("%s",&m_stu[count1].number);printf("\n姓名: ");gets(m_stu[count1].name);gets(m_stu[count1].name);printf("\n性别: ");scanf("%s",&m_stu[count1].sex);printf("\n电话号码: ");scanf("%s",&m_stu[count1].tel);printf("\n身份证号: ");scanf("%s",&m_stu[count1].id);printf("\n学号: ");scanf("%s",&m_stu[count1].study);printf("是否保存该学生信息？1-保存 2-放弃");scanf("%d",&j);if(j==1){FILE *info;                                           //保存至本地文件 info=fopen("d:\\information1.txt","at+");fwrite(&m_stu[count1],sizeof(struct student),1,info);fclose(info);printf("信息已保存至D:\\information1.tex 文件下，按任意键继续");count1++;}else printf("放弃保存，按任意键继续"); }
void seek_student()                                                                               //查询户籍信息函数                  {FILE *info;                                       info=fopen("d:\\information1.txt","rt");int i;printf("请输入该学生班内序号");scanf("%d",&i);if(i<1||i>50) printf("抱歉，该学生信息不存在");else {rewind(info);fseek(info,sizeof(struct student)*(i-1),0);fread(&m_stu[i-1],sizeof(struct student),1,info);printf("\n\n序号 姓名    性别 电话号码\t   身份证号\t\t学号\t");printf("\n\n%d   %s   %s   %s   %s    %s",i,m_stu[i-1].name,m_stu[i-1].sex,m_stu[i-1].tel,m_stu[i-1].id,m_stu[i-1].study);}}void change_student()                                                                           //修改户籍信息{int i=0,j,k,f;char h[100000];FILE *info; info=fopen("d:\\information1.txt","rt");printf("\n\t请输入要修改户籍信息的学生班内序号");scanf("%d",&j);if(j<1||j>50) printf("抱歉，该学生信息不存在");else {rewind(info);while(fgets(h,sizeof(struct student),info)!=NULL){fseek(info,sizeof(struct student)*i,0);fread(&m_stu[i],sizeof(struct student),1,info);i++;}}fclose(info);printf("\n该学生目前户籍信息为\n：");printf("\n\n序号 姓名    性别 电话号码\t   身份证号\t\t学号\t");printf("\n\n%d   %s   %s   %s   %s    %s",j,m_stu[j-1].name,m_stu[j-1].sex,m_stu[j-1].tel,m_stu[j-1].id,m_stu[j-1].study);printf("确定修改此学生信息？1- 修改 2- 返回");scanf("%d",&k);if(k==1){printf("\n姓名: ");gets(m_stu[j-1].name);gets(m_stu[j-1].name);printf("\n性别: ");scanf("%s",&m_stu[j-1].sex);printf("\n电话号码: ");scanf("%s",&m_stu[j-1].tel);printf("\n身份证号: ");scanf("%s",&m_stu[j-1].id);printf("\n学号: ");scanf("%s",&m_stu[j-1].study);} else return;                                     info=fopen("d:\\information1.txt","wt");for(f=0;f<i;f++){fseek(info,sizeof(struct student)*f,0);fwrite(&m_stu[f],sizeof(struct student),1,info);}fclose(info);printf("修改成功！");}void men2_student()                                                                           //二级菜单（学生成绩管理）{int choice=-1; while(choice!=0){printf("\n\t\t\t\t\t\t****************************\n");printf("\t\t\t\t\t\t**");  class_print();  printf("**\n");printf("\t\t\t\t\t\t**  班级学生成绩信息管理  **\n");printf("\t\t\t\t\t\t**  成绩信息已录入人数:");now2_student();printf("  **\n");printf("\t\t\t\t\t\t**     1.成绩录入系统     **\n");printf("\t\t\t\t\t\t**     2.成绩修改系统     **\n");printf("\t\t\t\t\t\t**     3.成绩查询系统     **\n");printf("\t\t\t\t\t\t**     4.综测排名系统     **\n");printf("\t\t\t\t\t\t**     0.返        回     **\n");printf("\t\t\t\t\t\t请选择"); scanf("%d",&choice); switch(choice){case 1:input_grade(); break;case 2:change_grade();break;case 3:seek_grade();break;case 4:printf("功能正在研发中，敬请期待..."); break;default:break;}getch();} }
void input_grade()                                                                                          // 成绩录入函数   ，录入信息保存至 D盘根目录下information2.txt文件下{int j;printf("学生成绩信息录入");printf("\n班内序号");scanf("%s",&g_stu[count2].number);printf("\n姓名: ");gets(g_stu[count2].name);gets(g_stu[count2].name);printf("\n高数: ");scanf("%s",&g_stu[count2].math);printf("\n英语:");scanf("%s",&g_stu[count2].English);printf("\nC语言:");scanf("%s",&g_stu[count2].Cprogram);printf("\n综测:");scanf("%s",&g_stu[count2].sumtest);printf("是否保存该学生信息？1-保存 2-放弃");scanf("%d",&j);if(j==1){FILE *info2;                                           //保存至本地文件 info2=fopen("d:\\information2.txt","at+");fwrite(&g_stu[count2],sizeof(struct grade),1,info2);fclose(info2);printf("信息已保存至D:\\information.tex2 文件下，按任意键继续");count2++;}else printf("放弃保存，按任意键继续"); }void seek_grade()                                                                                      //查询成绩信息函数                  {FILE *info2;                                       info2=fopen("d:\\information2.txt","rt");int i;printf("\n\t请输入该学生班内序号");scanf("%d",&i);if(i<1||i>50) printf("\n抱歉，该学生信息不存在");else {rewind(info2);fseek(info2,sizeof(struct grade)*(i-1),0);fread(&g_stu[i-1],sizeof(struct grade),1,info2);printf("\n\n序号 姓名  高数  英语  C语言  综测");printf("\n\n%d   %s   %s   %s   %s    %s",i,g_stu[i-1].name,g_stu[i-1].math,g_stu[i-1].English,g_stu[i-1].Cprogram,g_stu[i-1].sumtest);}}
void change_grade()                                                                                     //修改成绩信息   {int i=0,j,k,f;char h[100000];FILE *info; info=fopen("d:\\information2.txt","rt");printf("\n\t请输入要修改成绩信息的学生班内序号");scanf("%d",&j);if(j<1||j>50) printf("\n抱歉，该学生信息不存在");else {rewind(info);while(fgets(h,sizeof(struct grade),info)!=NULL){fseek(info,sizeof(struct grade)*i,0);fread(&g_stu[i],sizeof(struct grade),1,info);i++;}}fclose(info);printf("\n该学生目前成绩信息为\n：");printf("\n\n序号 姓名  高数 英语  C语言  综测");printf("\n\n%d   %s   %s   %s   %s    %s",j,g_stu[j-1].name,g_stu[j-1].math,g_stu[j-1].English,g_stu[j-1].Cprogram,g_stu[j-1].sumtest);printf("\n\t确定修改此学生信息？1- 修改 2- 返回");scanf("%d",&k);if(k==1){printf("\n姓名: ");gets(g_stu[j-1].name);gets(g_stu[j-1].name);printf("\n高数: ");scanf("%s",&g_stu[j-1].math);printf("\n英语: ");scanf("%s",&g_stu[j-1].English);printf("\nC语言: ");scanf("%s",&g_stu[j-1].Cprogram);printf("\n综测: ");scanf("%s",&g_stu[j-1].sumtest);} else return;                                     info=fopen("d:\\information2.txt","wt");if(info==NULL){printf("不能打开此文件，按任意键继续");getch();}for(f=0;f<i;f++){fseek(info,sizeof(struct grade)*f,0);fwrite(&g_stu[f],sizeof(struct grade),1,info);}fclose(info);printf("修改成功！");}
void men3_student()                                                                           //二级菜单（学生奖惩管理）
{
int choice=-1;
while(choice!=0){printf("\n");printf("\t\t\t\t\t\t****************************\n");printf("\t\t\t\t\t\t**");  class_print();  printf("**\n");printf("\t\t\t\t\t\t**  班级学生奖惩信息管理  **\n");printf("\t\t\t\t\t\t**  奖惩信息已录入人数:");now3_student();printf("  **\n");printf("\t\t\t\t\t\t**     1.奖惩录入系统     **\n");printf("\t\t\t\t\t\t**     2.奖惩修改系统     **\n");printf("\t\t\t\t\t\t**     3.奖惩查询系统     **\n");printf("\t\t\t\t\t\t**     0.返        回     **\n");printf("\t\t\t\t请选择"); scanf("%d",&choice);  switch(choice){case 1:input_reward();break;case 2:change_reward();break;case 3:seek_reward();break;case 0:printf("返回上一级");break;default :break;}getch();}
}
void input_reward()                                                                                // 奖惩录入函数      录入信息保存至D盘根目录下information3.txt文件下{int j;printf("学生奖惩信息录入");printf("\n班内序号: ");scanf("%s",&r_stu[count3].number);printf("\n姓名: ");gets(r_stu[count3].name);gets(r_stu[count3].name);printf("\n奖惩时间: ");scanf("%d.%d.%d",&r_stu[count3].time.year,&r_stu[count3].time.month,&r_stu[count3].time.day);printf("\n具体事件: ");gets(r_stu[count3].rewarding);gets(r_stu[count3].rewarding);printf("\n是否保存该学生信息？1-保存 2-放弃");scanf("%d",&j);if(j==1){FILE *info;                                           //保存至本地文件 info=fopen("d:\\information3.txt","at+");fwrite(&r_stu[count3],sizeof(struct reward),1,info);fclose(info);printf("\n信息已保存至D:\\information3.tex 文件下，按任意键继续");count3++;}else printf("放弃保存，按任意键继续"); }
void seek_reward()                                                                                //查询奖惩信息函数     根据学生班级序号              {FILE *info;                                       info=fopen("d:\\information3.txt","rt");int i;printf("\n\t请输入该学生班内序号");scanf("%d",&i);if(i<1||i>50) printf("\n抱歉，该学生信息不存在");else {rewind(info);fseek(info,sizeof(struct reward)*(i-1),0);fread(&r_stu[i-1],sizeof(struct reward),1,info);printf("\n\n序号  姓名    奖惩时间                 具体事件\t\t");printf("\n\n%d   %s   %d.%d.%d   %s   ",i,r_stu[i-1].name,r_stu[i-1].time.year,r_stu[i-1].time.month,r_stu[i-1].time.day,    r_stu[i-1].rewarding);}}
void change_reward()                                                                            //修改奖惩信息{int i=0,j,k,f;char h[100000];FILE *info; info=fopen("d:\\information3.txt","rt");printf("\n\t请输入要修改奖惩信息的学生班内序号");scanf("%d",&j);if(j<1||j>50) printf("\n抱歉，该学生信息不存在");else {rewind(info);while(fgets(h,sizeof(struct reward),info)!=NULL){fseek(info,sizeof(struct reward)*i,0);fread(&r_stu[i],sizeof(struct reward),1,info);i++;}}fclose(info);printf("\n该学生目前奖惩信息为\n：");printf("\n\n序号 姓名  奖惩时间    具体事件");printf("\n\n%d   %s   %d.%d.%d   %s   ",j,r_stu[j-1].name,r_stu[j-1].time.year,r_stu[j-1].time.month,r_stu[j-1].time.day  ,r_stu[j-1].rewarding);printf("\n\t确定修改此学生信息？1- 修改 2- 返回");scanf("%d",&k);if(k==1){printf("\n姓名: ");gets(r_stu[j-1].name);gets(r_stu[j-1].name);printf("\n奖惩时间: ");scanf("%d.%d.%d",&r_stu[j-1].time.year,&r_stu[j-1].time.month,&r_stu[j-1].time.day);printf("\n具体事件: ");scanf("%s",&r_stu[j-1].rewarding);} else return;                                     info=fopen("d:\\information3.txt","wt");for(f=0;f<i;f++){fseek(info,sizeof(struct reward)*f,0);fwrite(&r_stu[f],sizeof(struct reward),1,info);}fclose(info);printf("修改成功！");}
int now1_student()                                                                    //录入户籍信息学生数目       在菜单中 显示 已经录入学生人数
{int i=1;char j[100000];FILE *info;info=fopen("D:\\information1.txt","rt");rewind(info);while(fgets(j,sizeof(struct student),info)!=NULL){fseek(info,sizeof(struct student)*i,0);i++;}fclose(info);printf("%d",i-1);
}int now2_student()                                                                     //录入成绩信息学生数目     在菜单中 显示 已经录入学生人数
{int i=1;char j[100000];FILE *info;info=fopen("D:\\information2.txt","rt");rewind(info);while(fgets(j,sizeof(struct grade),info)!=NULL){fseek(info,sizeof(struct grade)*i,0);i++;}fclose(info);printf("%d",i-1);
}int now3_student()                                                                       //录入奖惩信息学生数目     在菜单中 显示 已经录入学生人数
{int i=1;char j[100000];FILE *info;info=fopen("D:\\information3.txt","rt");rewind(info);while(fgets(j,sizeof(struct reward),info)!=NULL){fseek(info,sizeof(struct reward)*i,0);i++;}fclose(info);printf("%d",i-1);
}
void class_print()                                                                         // 录入专业班级信息，并保存至D盘根目录下information0.txt文件下
{char major[20],class_number[4];FILE *info;info=fopen("d:\\information0.txt","rt");if(info==NULL){info=fopen("d:\\information0.txt","wt");printf("\n请输入专业 :");scanf("%s",&major);printf("\n请输入班级 :");scanf("%s",&class_number);fwrite(major,sizeof(major),1,info);fwrite(class_number,sizeof(class_number),1,info);printf("\n\t已保存专业班级信息！");fclose(info);info=fopen("d:\\information0.txt","rt");fread(&major,sizeof(major),1,info);fread(&class_number,sizeof(class_number),1,info);printf("%s",major);printf("%s班",class_number); }else {fread(&major,sizeof(major),1,info);fread(&class_number,sizeof(class_number),1,info);printf("%s",major);printf("%s班",class_number);fclose(info);}
}
void men4_student()                                                                               //二级菜单（班级财务管理）
{
int choice=-1;
while(choice!=0){printf("\n");printf("\t\t\t\t\t\t****************************\n");printf("\t\t\t\t\t********财务信息不可修改,请谨慎录入！******\n");printf("\t\t\t\t\t\t**  班级学生财务信息管理  **\n");printf("\t\t\t\t\t\t**     1.财务录入系统    **\n");printf("\t\t\t\t\t\t**     2.财务报表系统    **\n");printf("\t\t\t\t\t\t**     0.返        回     **\n");printf("\t\t\t\t\t\t请选择"); scanf("%d",&choice);  switch(choice){case 1:input_finance();break;case 2:report_finance(); break;case 3:case 0:printf("返回上一级");break;default :break;}getch();}
}void input_finance()                                                                        // 财务录入函数 ，录入后信息保存到D盘根目录下 information4.txt文件中{int j;printf("班级财务信息录入");printf("\n收支时间: ");scanf("%d.%d.%d",&f_class.time2.year,&f_class.time2.month,&f_class.time2.day );printf("\n具体事件: ");gets(f_class.thing);gets(f_class.thing);printf("\n财务类型(收入或开支): ");scanf("%s",&f_class.type);printf("\n流动金额(收入为正开支为负): ");scanf("%d",&f_class.i);printf("\n是否保存该财务信息？1-保存 2-放弃");scanf("%d",&j);if(j==1){FILE *info;                                           //保存至本地文件 info=fopen("d:\\information4.txt","at+");fwrite(&f_class,sizeof(struct finance),1,info);fclose(info);printf("\n信息已保存至D:\\information4.txt 文件下，按任意键继续");}else printf("放弃保存，按任意键继续"); }
void report_finance()                                                                                       // 财务信息报表
{    char h[100000];int sum=0,i=0;printf("\n收支时间   具体事件\t财务类型  流动金额\n");FILE *info;                                       info=fopen("d:\\information4.txt","rt");while(fgets(h,sizeof(struct finance),info)!=NULL){fseek(info,sizeof(struct finance)*i,0);fread(&f_class,sizeof(struct finance),1,info);i++;printf("\n%d.%d.%d %s          %s           %d\n",f_class.time2.year,f_class.time2.month,f_class.time2.day,  f_class.thing,f_class.type,f_class.i);sum=sum+f_class.i ;}printf("\n\t\t班费余额：%d元",sum);
}