#include <stdio.h>
#include <stdlib.h>
#define N 5
float cs1=0.0,cs2=0.0,cs3=0.0,cs4=0.0;
float ss[N]={0.0};
int flag1=0,flag2=0;
struct name
{ int id;
char name[20];
float c1;
float c2;
float c3;
float c4;
};

void srank(float a[],int b[],int n)
{
int i,j,temp2;
float temp1;
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++)
{
if(a[i]<a[j])
{
temp1=a[i];
a[i]=a[j];
a[j]=temp1;
temp2=b[i];
b[i]=b[j];
b[j]=temp2;
}
}
}
}
void Show(char s[],int n)
{
FILE *fp;
int i;
struct name t;
fp=fopen(s,"rb");
printf("ID\tNAME\tCO1\tCO2\tCO3\tCO4\n");
for(i=0;i<n;i++)
{
fseek(fp,sizeof(struct name)*i,SEEK_SET);
fread(&t,sizeof(struct name),1,fp);
printf("%-8d%-8s%.1f\t%.1f\t%.1f\t%.1f\n",t.id,t.name,t.c1,t.c2,t.c3,t.c4);
}
fclose(fp);
}
void C_Ave(char s[],int n)
{
FILE *fp;
struct name t;
int i;
fp=fopen(s,"rb");
for(i=0;i<n;i++)
{
fseek(fp,sizeof(struct name)*i,SEEK_SET);
fread(&t,sizeof(struct name),1,fp);
cs1+=t.c1;
cs2+=t.c2;
cs3+=t.c3;
cs4+=t.c4;
}
printf("ITEM\tCO1\tCO2\tCO3\tCO4\n");
printf("AVG\t%.1f\t%.1f\t%.1f\t%.1f\n",cs1/4,cs2/4,cs3/4,cs4/4);
flag1=1;
fclose(fp);
}
void S_Ave(char s[],int n)
{
FILE *fp;
int i;
struct name t;
fp=fopen(s,"rb");
printf("ID\tNAME\tSCORE\n");
for(i=0;i<n;i++)
{
fseek(fp,sizeof(struct name)*i,SEEK_SET);
fread(&t,sizeof(struct name),1,fp);
ss[i]=(t.c1+t.c2+t.c3+t.c4)/4;
printf("%-2d\t%-8s\t%.2f\n",t.id,t.name,ss[i]);
}
flag2=1;
fclose(fp);
}
void Save(char s[],int n)
{
FILE *fp;
struct name t;
int select;
int i;
fp=fopen(s,"rab");
if(flag1==1&&flag2==1)
{
fprintf(fp,"%f%f%f%f",cs1/4,cs2/4,cs3/4,cs4/4);
for(i=0;i<N;i++)
{
fprintf(fp,"%f ",ss[i]);
}
printf("SAVE SUCCESSFULLY!\nNow it is:\n");
printf("ID\tNAME\tCO1\tCO2\tCO3\tCO4\tAVG\n");
for(i=0;i<N;i++)
{
fseek(fp,sizeof(struct name)*i,SEEK_SET);
fread(&t,sizeof(struct name),1,fp);
printf("%-8d%-8s%.1f\t%.1f\t%.1f\t%.1f\t%.1f\n",t.id,t.name,t.c1,t.c2,t.c3,t.c4,ss[i]);
}
printf("- \t- \t%.1f\t%.1f\t%.1f\t%.1f\t-\n",cs1/4,cs2/4,cs3/4,cs4/4);
fclose(fp);
}
else
{
fclose(fp);
printf("you haven't calculated the ave_score!\n");
printf("Do you want to calculate the ave_score and then save it(1 for yes,2 for no)?\n");
scanf("%d",&select);
if(select==1)
{
C_Ave(s,n);
S_Ave(s,n);
Save(s,n);
}
}
}
void Rank(char s[],int n)
{
FILE *fp;
struct name t;
int b[n];
float a[n];
int select,i,j;
if(flag1==1&&flag2==1)
{
fp=fopen(s,"rb");
printf("Input course ID:(0 for ave_score ranking)\n");
scanf("%d",&select);
switch(select)
{
case 0:
for(i=0;i<n;i++)
{
fread(&t,sizeof(struct name),1,fp);
a[i]=(t.c1+t.c2+t.c3+t.c4)/4;
b[i]=i;
}
srank(a,b,n);
break;
case 1:
for(i=0;i<n;i++)
{
fread(&t,sizeof(struct name),1,fp);
a[i]=t.c1;
b[i]=i;
}
srank(a,b,n);
break;
case 2:
for(i=0;i<n;i++)
{
fread(&t,sizeof(struct name),1,fp);
a[i]=t.c2;
b[i]=i;
}
srank(a,b,n);
break;
case 3:
for(i=0;i<n;i++)
{
fread(&t,sizeof(struct name),1,fp);
a[i]=t.c3;
b[i]=i;
}
srank(a,b,n);
break;
case 4:
for(i=0;i<n;i++)
{
fread(&t,sizeof(struct name),1,fp);
a[i]=t.c4;
b[i]=i;
}
srank(a,b,n);
break;
default:
printf("Illegal input!");
}
printf("RANK\tID\tNAME\tSCORE\n");
for(i=0;i<n;i++)
{
fseek(fp,sizeof(struct name)*b[i],SEEK_SET);
fread(&t,sizeof(struct name),1,fp);
printf("%-8d%-8d%-8s%.1f\n",i+1,t.id,t.name,a[i]);
}
fclose(fp);
}
else
{
Save(s,n);
Rank(s,n);
}
}

int main(void)
{
FILE *fp;
int i;
struct name stu[N]=
{
{1,"a",90,80,88,70},
{2,"b",88,60,78,77},
{3,"c",90,95,90,100},
{4,"xueba",100,100,100,100},
{5,"xuezha",0,0,0,0}
};
char name[50];
printf("Please input the data file name:");
scanf("%s",name);
fp=fopen(name,"wb+");
fwrite(&stu,sizeof(struct name),N,fp);
fclose(fp);
do
{
printf("*************MENU*****************\n");
printf("1.Students' infomation\n");
printf("2.course avg_score\n");
printf("3.students' avg_score\n");
printf("4.output into file\n");
printf("5.cource ranking\n");
printf("6.exit\n");
printf("*************MENU*****************\n");
scanf("%d",&i);
switch(i)
{
case 1:
Show(name,N);
break;
case 2:
C_Ave(name,N);
break;
case 3:
S_Ave(name,N);
break;
case 4:
Save(name,N);
break;
case 5:
Rank(name,N);
break;
case 6:
break;
default:
printf("illegal input!\n");
}
} while(i!=6);
return 0;
}

这个代码包含了生成文件的代码，如果文件已经存在了，直接把那段代码注释掉就可以了

这个代码干啥的

吧主您已无敌

看到楼上突然觉得果然我已经不是一个理科生了

不懂

吧主，滚粗来

┬─┬ ノ( ' - 'ノ)