📄 chengji.cpp
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#include "stdio.h"
#include<string.h>
#include<stdlib.h>
#include"time.h"
/*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;
/*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;
}
void Student_DisplaySingle(int index)
{
printf("%-12s%-6s%-18s%-18s%-14s%-18s\n","学号","姓名","数据结构课程成绩","数据结构试验成绩","大学物理成绩","平均成绩");
printf("-------------------------------------------------------------------------------\n");
printf("%-12s%-12s%-18.2f%-14.2f%-14.2f%-4.2f\n",students[index].ID,students[index].Name,
students[index].Mark1,students[index].Mark2,students[index].Mark3,students[index].Average);
}
/*通过姓名返回数组下标*/
void Student_Select(int n)
{
while(1)
{
clock_t start, finish;
double usetime;
char name[20];
char id[20];
int index=0;
if(n==4)
{
printf("请输入要查询的学生的姓名:");
scanf("%s",&name);
getchar();
start=clock();
}
if(n==5)
{
printf("请输入要查询的学生的学号:");
scanf("%s",&id);
getchar();
start=clock();
}
finish = clock();
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);
}
usetime= (double)(finish - start) / CLOCKS_PER_SEC;
printf("程序用时%f秒",usetime);
printf("\n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];
}
num--;
}
getchar();
}
printf("是否继续?(y/n)");
if (getchar()=='n')
{
break;
}
}
}
/*显示全部学生信息*/
void Student_DisplayAll()
{
int i;
printf("%-12s%-6s%-18s%-18s%-14s%-8s\n","学号","姓名","数据结构课程成绩","数据结构试验成绩","大学物理成绩","平均成绩");
printf("-------------------------------------------------------------------------------\n");
for (i=0;i<num;i++)
{
printf("%-12s%-12s%-18.2f%-14.2f%-14.2f%-4.2f\n",students[i].ID,students[i].Name,
students[i].Mark1,students[i].Mark2,students[i].Mark3,students[i].Average);
}
printf("-------------------------------------------------------------------------------\n");
printf("总记录数：%d",num);
}
/*求平均值*/
float Avg(struct Student stu)
{
return (stu.Mark1+stu.Mark2+stu.Mark3)/3;
}
/*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("请输入数据结构课程成绩:");
scanf("%f",&students[num].Mark1);
getchar();
printf("请输入数据结构试验成绩:");
scanf("%f",&students[num].Mark2);
getchar();
printf("请输入大学物理成绩:");
scanf("%f",&students[num].Mark3);
getchar();
students[num].Average=Avg(students[num]);
num++;
printf("是否继续?(y/n)");
if (getchar()=='n')
{
break;
}
}
}
/*修改学生信息*/
void Student_Modify()
{
// float mark1,mark2,mark3;
while(1)
{
char id[20];
int index;
printf("请输入要修改的学生的学号:");
scanf("%s",&id);
getchar();
index=Student_SearchByIndex(id);
if (index==-1)
{
printf("学生不存在!\n");
}
else
{
printf("你要修改的学生信息为:\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("请输入数据结构课程成绩:");
scanf("%f",&students[index].Mark1);
getchar();
printf("请输入数据结构试验成绩:");
scanf("%f",&students[index].Mark2);
getchar();
printf("请输入大学物理成绩:");
scanf("%f",&students[index].Mark3);
getchar();
students[index].Average=Avg(students[index]);
}
printf("是否继续?(y/n)");
if (getchar()=='n')
{
break;
}
}
}
void Student_Sort(int p)
{
int i,j;
struct Student tmp;
switch(p)
{
case 1:
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;
}
}
}
break;
case 2:
for (i=0;i<num;i++)
{
for (j=1;j<num-i;j++)
{
if (students[j-1].Mark1<students[j].Mark1)
{
tmp=students[j-1];
students[j-1]=students[j];
students[j]=tmp;
}
}
}
break;
case 3:
for (i=0;i<num;i++)
{
for (j=1;j<num-i;j++)
{
if (students[j-1].Mark2<students[j].Mark2)
{
tmp=students[j-1];
students[j-1]=students[j];
students[j]=tmp;
}
}
}
break;
case 4:
for (i=0;i<num;i++)
{
for (j=1;j<num-i;j++)
{
if (students[j-1].Mark3<students[j].Mark3)
{
tmp=students[j-1];
students[j-1]=students[j];
students[j]=tmp;
}
}
}
break;
}
}
/*将学生信息从文件读出*/
void IO_ReadInfo()
{
FILE *fp;
int i;
if ((fp=fopen("F:\\数据结构试验\\9_6chengji\\grade.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("F:\\数据结构试验\\9_6chengji\\grade.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;
int i=0;
IO_ReadInfo();
while(1)
{
/*主菜单*/
printf("\n********************** 学生成绩管理系统****************************\n");
printf(" 1. 增加学生记录\n");
printf(" 2. 修改学生记录\n");
printf(" 3. 删除学生记录\n");
printf(" 4. 按姓名查询学生记录\n");
printf(" 5. 按学号查询学生记录\n");
printf(" 6. 成绩排序\n");
printf(" 7. 输出全部学生纪录\n");
printf(" 8. 清屏\n");
printf(" 0. 退出\n");
printf("********************************************************************\n");
printf(" 请选择(0-8):");
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(4);
break;
case 5:
Student_Select(5);
break;
case 6:
printf("请选择排序方式：1 按平均成绩 2 按数据结构课程成绩 3 按试验成绩 4 按大物成绩\n");
printf("请选择(1-4)：");
scanf("%d",&i);
Student_Sort(i);
Student_DisplayAll();
break;
case 7:
system("pause");
Student_DisplayAll();
break;
case 8:
system("pause");
system("cls");
break;
case 0:
exit(0);
break;
}
IO_WriteInfo();
}
}
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