#include <stdio.h>#include <stdlib.h>#define N 30/**为 struct students定义了一个新的名字 STU与 typedef struct students STU 等价**/typedef struct students{long id;char name[10];float score;}STU;void addscore(STU stu[],int n);void showscore(STU stu[],int n);void lowTOhigh(STU stu[],int n);void highTOlow(STU stu[],int n);int showlist(void);int main(){char choose;int n;STU stu[N];printf("你想输入多少名同学的信息：");scanf("%d",&n);while(1){choose=showlist();switch(choose){case 1:addscore(stu,n);break;case 2:showscore(stu,n);break;case 3:highTOlow(stu,n);showscore(stu,n);break;case 4:lowTOhigh(stu,n);showscore(stu,n);break;default:printf("Input error!\n");}}return 0;}void addscore(STU stu[],int n){int i;printf("***请输入学生的学号、姓名和成绩:\n(注意输入一项数据按一下回车键)\n");for(i=0;i<n;i++){scanf("%ld",&stu[i].id);scanf("%s",stu[i].name);scanf("%f",&stu[i].score);}}int showlist(void){int choose;printf("1.增加学生信息\n");printf("2.显示所有学生信息\n");printf("3.成绩由高到低排序\n");printf("4.成绩由低到高排序\n");printf("\n请选择：");scanf("%d",&choose);return choose;}void showscore(STU stu[],int n){int i;for(i=0;i<n;i++){printf("%ld%5s%6.1f\n",stu[i].id,stu[i].name,stu[i].score);}}void highTOlow(STU stu[],int n){int i,j,k;float temp1,temp2;for(i=0;i<n-1;i++){k=i;for(j=i+1;j<n;j++){if(stu[j].score>stu[k].score) k=j;}if(k!=i){temp1=stu[k].score;stu[k].score=stu[i].score;stu[i].score=temp1;temp2=stu[k].id;stu[k].id=stu[i].id;stu[i].id=temp2;}}}void lowTOhigh(STU stu[],int n){int i,j,k;float temp1,temp2;for(i=0;i<n-1;i++){k=i;for(j=i+1;j<n;j++){if(stu[j].score<stu[k].score) k=j;}if(k!=i){temp1=stu[k].score;stu[k].score=stu[i].score;stu[i].score=temp1;temp2=stu[k].id;stu[k].id=stu[i].id;stu[i].id=temp2;}}}
