用C语言做一个学生成绩管理系统 输入学生人数,录入学生成绩

#include
#include
#include
#include
#include
#include
#include
#include
#include
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
{

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
{

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
{

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
{

for (j=1;j
{

if (students[j-1].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
{

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
{

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
{

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();

}

}