学生成绩管理系统（链表处理+链表排序）

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct information{
    char number[11];
    char name[7];
    int English;
    int math;
    int physics;
    int C;
    int sum;
    double ave;
};//data

typedef struct student{
    struct information data;
    struct student *next;
}STU;

STU * sort(STU *head);
// void exchange(STU *a,STU *b);
STU * Creatlist(STU *head){
    STU *p=NULL;
    int num;
    scanf("%d",&num);//输入的是学生的个数 
    if(head==NULL){
        STU *tail=NULL;
        while(num-->0){
            p=(STU *)malloc(sizeof(STU ));
//        //输入学生信息  
            scanf("%s",p->data.number);
            scanf("%s",p->data.name);
            scanf("%d %d %d %d",&p->data.English,&p->data.math,&p->data.physics,&p->data.C);
//            scanf("%d",&p->data.math);
//            scanf("%d",&p->data.physics);
//            scanf("%d",&p->data.C);
        //    
//            printf("here");
            if(head==NULL){
//                printf("GOT");
                head=p;//初次输入1时第一轮 
            }
            else{
                tail->next=p;
            }
            tail=p;
        }tail->next=NULL;
        //sb题目创建完列表都要排序的吗
        p=head;
        while(p!=NULL){
        double average=0.00;
        int sum_=0;
        sum_=p->data.English+p->data.math+p->data.physics+p->data.C;
        average=(sum_)/4.00*1.00;
        p->data.ave=average;
        p->data.sum=sum_;
        p=p->next;
        }
        //
        
    }else {
        p=head;
        while(p->next!=NULL){
            p=p->next;
        }
        STU *tail=p;
        while(num-->0){
            p=(STU *)malloc(sizeof(STU ));
        //第二次输入学生信息 
            scanf("%s",p->data.number);
            scanf("%s",p->data.name);
            scanf("%d %d %d %d",&p->data.English,&p->data.math,&p->data.physics,&p->data.C);
        //    
            tail->next=p;
            tail=p;
        }tail->next=NULL;
    }
    return head;
}
STU * Change(STU *head){
    char symbol[11];
    scanf("%s",symbol);//读入待查找人
    STU *p=head;
    while(p!=NULL){
        if(strcmp(p->data.number,symbol)==0){
            int judge=0,score=0;
            scanf("%d",&judge);//读入待修改成绩 
            scanf("%d",&score);
            switch(judge){
                case 1:
                    p->data.English=score; 
                    break;
                case 2:
                    p->data.math=score;
                    break;
                case 3:
                    p->data.physics=score;
                    break;
                case 4:
                    p->data.C=score;
                    break;
                default: break; 
            }
            break;//改变之后跳出查找 
        }
        p=p->next;
    }
    return head;
}

STU * Print_all(STU *head){
    head=sort(head);
    STU *p=head;
    while(p!=NULL){
        printf("%s ",p->data.number);
        printf("%s ",p->data.name);
        printf("%d ",p->data.English);
        printf("%d ",p->data.math);
        printf("%d ",p->data.physics);
        printf("%d",p->data.C);
        printf("\n");
        p=p->next;
    }
    return head;
}



 STU * Average(STU *head){
     STU *p=head;
     while(p!=NULL){
         double average=0.00;
         int sum_=0;
         sum_=p->data.English+p->data.math+p->data.physics+p->data.C;
         average=(sum_)/4.00*1.00;
         p->data.ave=average;
         p->data.sum=sum_;
         p=p->next;
 //        printf("##%s %d %f##\n",p->data.name,p->data.sum,p->data.ave);
     }
     head=sort(head);
     p=head;
     while(p!=NULL){
         printf("%s ",p->data.number);
         printf("%s ",p->data.name);
         printf("%.2f",p->data.ave);
         printf("\n");
         p=p->next;
     }
     return head;    
 }

// STU * sort(STU *head){
    
//     return head;
// }

STU * sort(STU *head){
    STU *loc_head,*tail=NULL,*last=NULL,*p;
    p=head;
    STU *mid=NULL;
    loc_head=(STU *)malloc(sizeof(STU));
    loc_head->next=head;
    for(tail=NULL;loc_head->next!=tail;tail=p){
        p=loc_head->next;//如果用 p=head;为什么会传址失败呢？
        for(last=loc_head;p->next!=tail;last=last->next,p=p->next){
            mid=p->next; 
            if((p->data.ave)>(mid->data.ave)){
                last->next=mid;
                p->next=mid->next;
                mid->next=p;
                p=last->next;
            }
        }
    }
    head=loc_head->next;
    free(loc_head);
    return head;
}


STU * subPrint(STU *head){
    STU *p=head;
    while(p!=NULL){
        double average=0.00;
        int sum_=p->data.English+p->data.math+p->data.physics+p->data.C;
        average=(sum_)/4.00*1.00;
        p->data.ave=average;
        p->data.sum=sum_;
        p=p->next;
//        printf("##%s %d %f##\n",p->data.name,p->data.sum,p->data.ave);
    }
    head=sort(head);
    p=head;
    while(p!=NULL){
        printf("%s ",p->data.number);
        printf("%s ",p->data.name);
        printf("%d ",p->data.sum);
        printf("%.2f",p->data.ave);
        printf("\n");
        p=p->next;
    }
    return head;
}

STU * (*menu[5])(STU *)={Creatlist,Print_all,Change,Average,subPrint};
int main(){
    STU *head=NULL;
    int flag;
    //input flag
    scanf("%d",&flag);
    while(flag!=0){
        head=(*menu[flag-1])(head);
        scanf("%d",&flag);
    }
    return 0;
}