《C语言编写 学生成绩管理系统》

/* (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();

     }

}