C语言学生成绩管理系统（简易版）

 #include<stdio.h>
 #include<stdlib.h>
 #include<string.h>

 int readstudents(struct students stu[]);        //读取学生信息
 int readsexcode(struct sexcode sex[]);          //读取性别代码
 int readcollegecode(struct collegecode colle[]);        //读取学院代码
 void transform(struct students stu[],struct sexcode sexy[],struct collegecode colle[],int a,int b,int c);               //录入
 void namesort(struct students stu[],int a);             //按照姓名排序
 void averagesort(struct students stu[],int a);          //平均分排序
 void searchcollege(struct students stu[],int a);        //按学院搜索学生
 void namesearch(struct students stu[],int a);           //按名字搜索
 void printstudent(struct students stu[],struct sexcode sex[],struct collegecode colle[],int a,int b,int c);         //输出
 void change(struct students stu[],int a);
 int passwordfun();
 void passwordchange();
 void averagefun(struct students stu[],int a);

 struct students{
     int num;
     char name[];
     int sexnum;
     char sex[];
     int collegenum;
     char college[];
     int score[];
     float average;
 };
 struct sexcode{
     int sexnum;
     char sex[];
 };
 struct collegecode{
     int collegenum;
     char college[];
 };

 int main()
 {
     int a,b,c;
     int choice;
     struct students stu[];
     struct sexcode sexy[];
     struct collegecode colle[];
     int t = passwordfun();
     if(t == ){
         printf("请使用正确密码重新登陆程序！\n");
         return ;
     }
     while(){
         system("cls");
         printf("***********学生成绩系统菜单************ \n*        1. 原始文件读取              *\n*        2. 按姓名排序，输出          *\n*        3. 按平均成绩排序，输出      *\n*        4. 输出给定学院学生          *\n*        5. 修改给定学生成绩信息      *\n*        6. 按姓名查询学生，输出      *\n*        7. 修改系统密码              *\n*        0. 返回上一级菜单            *\n***************************************\n");
         scanf("%d",&choice);
         switch(choice){
             case :    system("cls");
                 a = readstudents(stu);
                 b = readsexcode(sexy);
                 c = readcollegecode(colle);
                 transform(stu,sexy,colle,a,b,c);
                 averagefun(stu,a);
                 printf("原始文件读取完毕！\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 namesort(stu,a);
                 printstudent(stu,sexy,colle,a,b,c);
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 averagesort(stu,a);
                 printstudent(stu,sexy,colle,a,b,c);
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 searchcollege(stu,a);
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 change(stu,a);
                 printf("修改成功！\n");
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 namesearch(stu,a);
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 passwordchange();
                 printf("\n0. 返回上一级菜单 \n");
                 scanf("%d",&choice);
                 if(choice == ) break;
             case : system("cls");
                 printf("欢迎使用，下次再见！\n");
                 system("pause");
                 exit();
         }
     }
     return ;
 }
 int readstudents(struct students stu[])     //读取学生信息
 {
     int i = ;
     FILE *fp;
     fp = fopen("D:\\abc\\Student_Info.txt","r+");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     fscanf(fp,"%d",&stu[i].num);
     while(!feof(fp)){
         fscanf(fp,"%s%d%d",stu[i].name,&stu[i].sexnum,&stu[i].collegenum);
         for(int j =  ;j < ; j++ ){
             fscanf(fp,"%d",&stu[i].score[j]);
         }
         i++;
         fscanf(fp,"%d",&stu[i].num);
     }
     fclose(fp);
     return i;
 }
 int readsexcode(struct sexcode sexy[])      //读取学生性别信息
 {
     int i = ;
     FILE *fp;
     fp = fopen("D:\\abc\\S_Info.txt","r");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     fscanf(fp,"%d",&sexy[i].sexnum);
     while(!feof(fp)){
         fscanf(fp,"%s",sexy[i].sex);
         i++;
         fscanf(fp,"%d",&sexy[i].sexnum);
     }
     fclose(fp);
     return i;
 }
 int readcollegecode(struct collegecode colle[])     //读取学生学院信息
 {
     int i = ;
     FILE *fp;
     fp = fopen("D:\\abc\\C_Info.txt","r");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     fscanf(fp,"%d",&colle[i].collegenum);
     while(!feof(fp)){
         fscanf(fp,"%s",colle[i].college);
         i++;
         fscanf(fp,"%d",&colle[i].collegenum);
     }
     fclose(fp);
     return i;
 }
 void averagefun(struct students stu[],int a)        //平均分
 {
     for(int i = ; i < a; i++){
         int sum = ;
         for(int j = ; j < ; j++){
             sum = sum + stu[i].score[j];
         }
         stu[i].average = 1.0 * sum / ;
     }
     return ;
 }
 void namesort(struct students stu[],int a)          //按姓名排序
 {
     for(int i = ; i < a-; i++){
         for(int j = i+; j < a ; j++){
             if(strcmp(stu[i].name,stu[j].name) < ){
                 struct students temp = stu[i];
                 stu[i] = stu[j];
                 stu[j] = temp;
             }
         }
     }
     return ;
 }
 void averagesort(struct students stu[],int a)           //  按平均分排序
 {
     for(int i = ; i < a-; i++){
         for(int j = i+; j < a ; j++){
             if(stu[i].average < stu[j].average){
                 struct students temp = stu[i];
                 stu[i] = stu[j];
                 stu[j] = temp;
             }
         }
     }
     return ;
 }
 void printstudent(struct students stu[],struct sexcode sexy[],struct collegecode colle[],int a,int b,int c)         //输出信息
 {
     for(int i = ;i < a; i++){
         printf("%d%8s%4s%12s",stu[i].num,stu[i].name,stu[i].sex,stu[i].college);
         for(int j = ; j < c; j++){
             printf("%4d",stu[i].score[j]);
         }
         printf("%7.2f\n",stu[i].average);
     }
     return ;
 }
 void transform(struct students stu[],struct sexcode sexy[],struct collegecode colle[],int a,int b,int c)        //修改信息
 {
     for(int i = ; i < a; i++){
         for(int j = ; j < b; j++){
             if(stu[i].sexnum == sexy[j].sexnum){
                 strcpy(stu[i].sex,sexy[j].sex);
                 break;
             }
         }
         for(int j = ; j < c; j++){
             if(stu[i].collegenum == (colle[j].collegenum - )){
                 strcpy(stu[i].college,colle[j].college);
                 break;
             }
         }
     }
 }

 void searchcollege(struct students stu[],int a)         //查找学院并输出
 {
     char collegename[];
     printf("请输入需要查找的学院的名称：\n") ;
     scanf("%s",collegename);
     for(int i = ;i < a; i++){
         if(strcmp(stu[i].college,collegename) == ){
             printf("%d%8s%4s%12s",stu[i].num,stu[i].name,stu[i].sex,stu[i].college);
             for(int j = ; j < ; j++){
                 printf("%4d",stu[i].score[j]);
             }
             printf("%7.2f\n",stu[i].average);
         }
     }
     return ;
 }
 void namesearch(struct students stu[],int a)        //按姓名查找
 {
     printf("请输入需要查找的学生的姓名：\n");
     char name[];
     scanf("%s",name);
     for(int i = ;i < a; i++){
         if(strcmp(stu[i].name,name) == ){
             printf("%d%8s%4s%12s",stu[i].num,stu[i].name,stu[i].sex,stu[i].college);
             for(int j = ; j < ; j++){
                 printf("%4d",stu[i].score[j]);
             }
             printf("%7.2f\n",stu[i].average);
         }
     }
     return ;
 }
 void change(struct students stu[],int a)        //按名字搜索修改分数
 {
     char name[];
     printf("请输入需要修改成绩的学生的姓名：\n");
     scanf("%s",name);
     printf("请输入改学生各科成绩，不需要修改的按原样输入：\n");
     for(int i = ;i < a; i++){
         if(strcmp(stu[i].name,name) == ){
             for(int j = ; j <= ; j++){
                 printf("第%d门成绩:    ",j);
                 scanf("%d",&stu[i].score[j-]);
                 printf("\n");
             }
         }
     }
     int i = ;
     FILE *fp;
     fp = fopen("D:\\abc\\Student_Info.txt","w");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     while(i<){
         fprintf(fp,"%d %s %d %d",stu[i].num,stu[i].name,stu[i].sexnum,stu[i].collegenum);
         for(int j =  ;j < ; j++ ){
             fprintf(fp," %d",stu[i].score[j]);
             if(j == ){
                 fprintf(fp,"\n");
             }
         }
         i++;
     }
     fclose(fp);
     return ;
 }
 int passwordfun()           //密码
 {
     char password_1[],password_2[],password_3[];
     int i = ;
     FILE *fp;
     fp = fopen("D:\\abc\\password.txt","r");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     fscanf(fp,"%s",password_2);
     fclose(fp);
     if(password_2[i] == '\0'){          //当检测到密码文本为空时
         printf("欢迎使用学生成绩管理系统！\n首次使用系统，您可以直接进入主菜单，进入主菜单后请及时修改密码！\n");
         system("pause");
         return ;
     }
     else
         {
         printf("请输入系统密码：\n");

                //保存输入的密码
            char s[];
            int t,n_,x;
         for(x=;x<;x++){
             s[x]=getch();
             if(s[x]=='\r')    break;
             printf("*");
         }
         s[x]='\0';
         for(t=;t<;t++){        //将输入的密码存放在password_1中
             password_1[t]=s[t];
         }
         for(i = ; password_2[i] != '\0'; i++){
             if(password_2[i] <=  && password_2[i] >= ){                 //password_2为真实密码
                 password_3[i] = password_2[i] - ;      //密码密文加密（+3）
             }else{
                 password_3[i] =  - password_3[i];
             }                                           //password_3为按算法处理后的真实密码
         }
         password_3[i] = '\0';
         if(strcmp(password_1,password_3) == ){
             return ;
         }else{
             printf("密码错误！\n程序结束！请使用正确密码重新登入程序！\n");
             system("pause");
             return ;
         }
     }
 }
 void passwordchange()       //密码修改
 {
     FILE *fp;
     char newpassword_1[];
     char newpassword_2[];
     int i = ;
     printf("请输入新的密码：\n");
     scanf("%s",newpassword_1);
     for(i = ; newpassword_1[i] != '\0'; i++){
         if(newpassword_1[i] +  <= ){
             newpassword_2[i] = newpassword_1[i] + ;
         }else{
             newpassword_2[i] = newpassword_1[i] +  -;
         }
     }
     newpassword_2[i] = '\0';
     fp = fopen("D:\\abc\\password.txt","w");
     if(fp == ){
         printf("can not open this file\n");
         exit ();
     }
     fprintf(fp,"%s",newpassword_2);
     fclose(fp);
     printf("密码修改成功！\n");
     return ;
 }