《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(); } }