/* (程序头部凝视開始)
* 程序的版权和版本号声明部分
* Copyright (c) 2011, 烟台大学计算机学院学生
* All rights reserved.
* 文件名： 学生成绩管理系统
* 作 者： 刘江波
* 完毕日期： 2012 年 6 月 23 日
* 版 本 号： v.623

* 对任务及求解方法的描写叙述部分
* 程序头部的凝视结束
*/

#include "stdio.h"#include"string"/*定义学生结构体*/struct Student{     char ID[20];     char Name[20];     float Mark1;     float Mark2;     float Mark3;     float Average;};/*声明学生数组及学生数量*/struct Student students[1000];int num=0; /*求平均值*/float Avg(struct Student stu){     return (stu.Mark1+stu.Mark2+stu.Mark3)/3;} /*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("%10s%10s%8s%8s%8s%10s\n","学号","姓名","成绩","成绩","成绩","平均成绩");     printf("-------------------------------------------------------------\n");     printf("%10s%10s%8.2f%8.2f%8.2f%10.2f\n",students[index].ID,students[index].Name,              students[index].Mark1,students[index].Mark2,students[index].Mark3,students[index].Average);} /*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("请输入成绩:");         scanf("%f",&students[num].Mark1);         getchar();          printf("请输入成绩:");         scanf("%f",&students[num].Mark2);         getchar();          printf("请输入成绩:");         scanf("%f",&students[num].Mark3);         getchar();          students[num].Average=Avg(students[num]);         num++;          printf("是否继续?(y/n)");         if (getchar()==‘n‘)         {              break;         }     } } /*改动学生信息*/void Student_Modify(){     //float mark1,mark2,mark3;     while(1)     {         char id[20];         int index;         printf("请输入要改动的学生的学号:");         scanf("%s",&id);         getchar();         index=Student_SearchByIndex(id);         if (index==-1)         {              printf("学生不存在!\n");         }         else         {              printf("你要改动的学生信息为:\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("请输入成绩:");              scanf("%f",&students[index].Mark1);              getchar();              printf("请输入成绩:");              scanf("%f",&students[index].Mark2);              getchar();              printf("请输入成绩:");              scanf("%f",&students[index].Mark3);              getchar();              students[index].Average=Avg(students[index]);         }         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;         }     }} /*按平均值排序*/void Student_SortByAverage(){     int i,j;     struct Student tmp;     for (i=0;i<num;i++)     {         for (j=1;j<num-i;j++)         {              if (students[j-1].Average<students[j].Average)              {                   tmp=students[j-1];                   students[j-1]=students[j];                   students[j]=tmp;              }         }     }} /*显示学生信息*/void Student_Display(){     int i;     printf("%10s%10s%8s%8s%8s%10s\n","学号","姓名","成绩","成绩","成绩","平均成绩");     printf("-------------------------------------------------------------\n");     for (i=0;i<num;i++)     {         printf("%10s%10s%8.2f%8.2f%8.2f%10.2f\n",students[i].ID,students[i].Name,              students[i].Mark1,students[i].Mark2,students[i].Mark3,students[i].Average);     }} /*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------ 学生成绩管理系统------\n");         printf("1. 添加学生记录\n");         printf("2. 改动学生记录\n");         printf("3. 删除学生记录\n");         printf("4. 按姓名查询学生记录\n");         printf("5. 按平均成绩排序\n");         printf("6. 退出\n");         printf("请选择(1-6):");         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:              Student_SortByAverage();              Student_Display();              break;         case 6:              exit(0);              break;         }         IO_WriteInfo();     }}