给一个我以前写过的吧，功能应该差不多
#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <cmath>
using namespace std;
/*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;
}
}
}
/*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. 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();
}
}
追问最好是直接按照题目完整的写一下，我就一小白，你给我相识的我也改不出来。大学计算机课，根本不会，我不是学这个的，麻烦各位专业的大师赐教了谢谢。如果你觉得麻烦的话，就不麻烦您了，我等别人，谢谢您的帮助
追答/*统计每个等级的人数以及所占的百分比*/
void Showgrade()
{
int x1 = 0;
int x2 = 0;
int x3 = 0;
int x4 = 0;
int x5 = 0;
for(int i = 0; i < num; i++)
{
float temp = students[i].Mark1;
if(temp >= 90.00 ) x1++;
else if(temp >= 80.00 ) x2++;
else if(temp >= 80.00 ) x3++;
else if(temp >= 80.00 ) x4++;
else x5++;
}
printf("优秀：%.2lf\n",(double)(x1) / (double)(num));
printf("良好：%.2lf\n",(double)(x2) / (double)(num));
printf("中等：%.2lf\n",(double)(x3) / (double)(num));
printf("及格：%.2lf\n",(double)(x4) / (double)(num));
printf("不及格：%.2lf\n",(double)(x5) / (double)(num));
}
追问能再帮一下我吗，把2. 计算课程考试的最高分、最低分、平均分；并统计不及格人数；编一下。我自己变了每次都是出现一个错误，不知道哪里错了，谢谢
追答void Show2()
{
int PassNum = 0；
float Max = students[0].Mark1;
float Min = students[0].Mark1;
float Average = 0.00;
for(int i = 0; i < num; i++)
{
float temp = students[i].Mark1;
if(temp >= 60.00 ) PassNum ++;
Max = Max < temp ? temp : Max;
Min = Min > temp ? temp : Min;
Average += temp;
}
Average /= num;
printf("最高分：%.2lf\n",Max );
printf("最低分：%.2lf\n",Min );
printf("平均分：%.2lf\n",Average );
printf("及格人数：%d\n",PassNum );
}
上面那些 Mark2 Mark3 你要是不要相关的都可以直接删掉