本人初学c语言，不会做题，希望各位能救个急！！
输入10个学生的3门课的成绩，分别用函数求：
(1)每个学生的平均分；
（2）按学生平均分降序排列输出学生信息；
（3）每门课的平均分；
（4）统计不及格学生，输出其相应信息；
（5）编写一菜单主函数，菜单内容包括以上4点。
[解决办法]
#include <stdio.h>//通讯录//排序还是有点问题的#include <conio.h>#include <string.h>#include <stdlib.h>#define N 100int M=5;struct student{ char num[10];char name[10];char tel[10];};void myprint(){ printf(" |-----------------------------------------------|\n"); printf(" 请输入选项\n"); printf("\n"); printf(" 1`创建通讯录\n"); printf(" 2`显示通讯录\n"); printf(" 3`查询通讯录\n"); printf(" 4`修改通讯录\n"); printf(" 5`添加通讯录\n"); printf(" 6`删除通讯录\n"); printf(" 7`排序通讯录|\n"); printf(" 0`退出\n"); printf("\n");}void mycreat(struct student *p,int n){ struct student *q=p; FILE *fp=NULL; fp=fopen("d:\\jilu.dat","w"); if(fp==NULL){printf("error"); return;} for(p=q;p-q<n;p++) { printf("\n"); printf("第%d条记录:\n",p-q+1); printf("学号:"); do {gets(p->num);} while(strcmp(p->num,"")==0); printf("姓名:"); gets(p->name); printf("电话:"); gets(p->tel); fprintf(fp,"%23s%15s%15s\n",p->num,p->name,p->tel); }}void mydisplay(struct student *p,int n){ FILE *fp=NULL; fp=fopen("d:\\jilu.dat","r"); if(fp==NULL){printf("error"); return;} system("cls"); printf(" 学号 姓名 电话\n"); while(n>0) { fscanf(fp,"%23s%15s%15s",p->num,p->name,p->tel); printf("%23s%15s%15s\n",p->num,p->name,p->tel); p++;n--; }}void mysearch(struct student *p,int n){ struct student *q=p; int flag=0; char c='\0',nm[10]="",nam[10]=""; printf("\n按照学号查询(h)或姓名查询(m):\n"); c=getche(); if(c=='h'||c=='H') { printf("请输入要查询记录的学号:");gets(nm); for(p=q;p-q<n;p++) if(strcmp(nm,p->num)==0) { printf(" 学号 姓名 电话\n"); printf("%23s%15s%15s\n",p->num,p->name,p->tel); flag=1; } if(flag==0) printf("wrong...\n"); } else if(c=='m'||c=='M') { printf("请输入要查询记录的姓名:");gets(nam); for(p=q;p-q<n;p++) if(strcmp(nam,p->name)==0) { printf(" 学号 姓名 电话\n"); printf("%23s%15s%15s\n",p->num,p->name,p->tel); flag=1; } if(flag==0) printf("wrong...\n"); } else printf("wrong...\n");}void mymodify(struct student *p,int n){ struct student *q=p; FILE *fp=NULL; char nam[10]=""; mydisplay(p,n); printf("请输入您想要修改记录的姓名:\n");gets(nam); for(p=q;p-q<n;p++) if(strcmp(nam,p->name)==0) break; if(p-q==n) printf("wrong..."); else { printf("请输入正确的学号:"); do gets(p->num); while(strcmp(p->num,"")==0);// printf("请输入正确的姓名:");// gets(p->name); printf("请输入正确的电话:"); gets(p->tel); } fp=fopen("d:\\jilu.dat","w"); if(fp==NULL){printf("error"); exit(0);} for(p=q;p-q<n;p++) fprintf(fp,"%23s%15s%15s\n",p->num,p->name,p->tel); fclose(fp);}void myadd(struct student *p,int n){ FILE *fp=NULL; struct student *q=p; char c='\n',tempnum[10]="",tempname[10]="",temptel[10]=""; printf("\n"); while(strcmp(p->num,"")!=0) { printf("%23s%15s%15s\n",p->num,p->name,p->tel); p++; } n=p-q; do { printf("请输入新纪录的学号:"); do gets(tempnum); while(strcmp(tempnum,"")==0); printf("请输入新纪录的姓名:"); gets(tempname); printf("请输入新纪录的电话:"); gets(temptel); for(p=q;p-q<n;p++) if(strcmp(tempnum,p->num)==0||strcmp(temptel,p->tel)==0) { printf("学号或电话号码需要重新输入吗(Y/N)?"); c=getche(); putchar('\n'); break; } if(p-q==n) { strcpy(p->num,tempnum); strcpy(p->name,tempname); strcpy(p->tel,temptel); break; } }while(c=='y'||c=='Y'); fp=fopen("d:\\jilu.dat","w"); if(fp==NULL){printf("error"); return;} for(p=q;p-q<=n;p++) fprintf(fp,"%23s%15s%15s\n",p->num,p->name,p->tel); fclose(fp); M++;}void mydelete(struct student *p,int n){ FILE *fp=NULL; struct student *q=p; char c[10]="",tempnum[10]="",tempname[10]="",temptel[10]="",choose='\0'; mydisplay(p,n); printf("选择删除记录的方式:学号(h)姓名(m)"); choose=getche(); printf("\n"); if(choose=='m'||choose=='M') { printf("删除的记录:"); gets(c); for(;p-q<n;p++) if(strcmp(c,p->name)==0) break; if(p-q<n) for(;p-q<n-1;p++) { strcpy(p->num,(p+1)->num); strcpy(p->name,(p+1)->name); strcpy(p->tel,(p+1)->tel); } else printf("no\n"); } else if(choose=='h'||choose=='H') { printf("删除的记录:"); gets(c); for(;p-q<n;p++) if(strcmp(c,p->num)==0) break; if(p-q<n) for(;p-q<n-1;p++) { strcpy(p->num,(p+1)->num); strcpy(p->name,(p+1)->name); strcpy(p->tel,(p+1)->tel); } else printf("no"); } else printf("wrong\n"); fp=fopen("d:\\jilu.dat","w"); if(fp==NULL){printf("error"); return;} for(p=q;p-q<n-1;p++) fprintf(fp,"%23s%15s%15s\n",p->num,p->name,p->tel); fclose(fp); M--;}void mysort(struct student *p,int n)//排序还是有点问题的{ FILE *fp=NULL; struct student *q=p,*w=p,*a=p; char temp[10]="",c1='\0',c2='\0'; mydisplay(p,n); printf("选择按照学号(h)或姓名(m)排序:\n"); c1=getche(); if(c1=='h'||c1=='H') { printf("升序(s)或者降序(j)排列:"); c2=getche(); if(c2=='s'||c2=='S') for(;p-a<n;p++) { w=p; for(q=p+1;q-a<n;q++) if(strcmp(w->num,q->num)>0) w=q; strcpy(temp,w->num); strcpy(w->num,p->num); strcpy(p->num,temp); strcpy(temp,w->name); strcpy(w->name,p->name); strcpy(p->name,temp); strcpy(temp,w->tel); strcpy(w->tel,p->tel); strcpy(p->tel,temp); } else if(c2=='j'||c2=='J') for(;p-a<n;p++) { w=p; for(q=p+1;q-a<n;q++) if(strcmp(w->num,q->num)<0) w=q; strcpy(temp,w->num); strcpy(w->num,p->num); strcpy(p->num,temp); strcpy(temp,w->name); strcpy(w->name,p->name); strcpy(p->name,temp); strcpy(temp,w->tel); strcpy(w->tel,p->tel); strcpy(p->tel,temp); } else printf("555wrong...\n"); } else if(c1=='m'||c1=='M') { printf("升序(s)或者降序(j)排列:"); c2=getche(); if(c2=='s'||c2=='S') for(;p-a<n;p++) { w=p; for(q=p+1;q-a<n;q++) if(strcmp(w->name,q->name)>0) w=q; strcpy(temp,w->num); strcpy(w->num,p->num); strcpy(p->num,temp); strcpy(temp,w->name); strcpy(w->name,p->name); strcpy(p->name,temp); strcpy(temp,w->tel); strcpy(w->tel,p->tel); strcpy(p->tel,temp); } else if(c2=='j'||c2=='J') for(;p-a<n;p++) { w=p; for(q=p+1;q-a<n;q++) if(strcmp(w->name,q->name)<0) w=q; strcpy(temp,w->num); strcpy(w->num,p->num); strcpy(p->num,temp); strcpy(temp,w->name); strcpy(w->name,p->name); strcpy(p->name,temp); strcpy(temp,w->tel); strcpy(w->tel,p->tel); strcpy(p->tel,temp); } else printf("555wrong...\n"); } else printf("555wrong...\n"); fp=fopen("d:\\jilu.dat","w"); if(fp==NULL){printf("error"); return;} for(p=a;p-a<=n;p++) fprintf(fp,"%23s%15s%15s\n",p->num,p->name,p->tel); fclose(fp);}main(){ char choose='\0',yes_no='\0'; struct student record[N]={0}; do { myprint(); printf(" :-)请选择(0-7):"); choose=getche(); switch(choose) { case '1':mycreat(record,M);break; case '2':mydisplay(record,M);break; case '3':mysearch(record,M);break; case '4':mymodify(record,M);break; case '5':myadd(record,M);break; case '6':mydelete(record,M);break; case '7':mysort(record,M);break; case '0':exit(0); default :printf("\nerror...\n"); } printf("\n :-)继续选择吗(y/n)?\n"); do {yes_no=getch();} while(yes_no!='Y'&&yes_no!='y'&&yes_no!='N'&&yes_no!='n'); }while(yes_no=='Y'||yes_no=='y');}