快速排序、二分查找 学生信息（可进行姓名查找）

代码：

#include<stdio.h>#include<stdlib.h>#define m 3struct student{    long cardnum;;    char name[20];    char academy[20];    long class_num;};void input(struct student stu[m]){    int j,i=1;    for(j=0;j<m;j++)    {        printf("请输入第%d个同学的卡号:",i);        scanf("%ld",&stu[j].cardnum);        printf("请输入第%d个同学的姓名:",i);        scanf("%s",stu[j].name);        printf("请输入第%d个同学的院系:",i);        scanf("%s",stu[j].academy);        printf("请输入第%d个同学的班级:",i);        scanf("%ld",&stu[j].class_num);        i++;        printf("--------------------------\n");    }}void quicksort(struct student stu[m],int left,int right){    int i,j;    struct student p;    if(left<right)    {        i=left+1;        j=right;        while(i<j)        {            if(stu[i].cardnum > stu[left].cardnum)            {               p=stu[i];               stu[i]=stu[left];               stu[left]=p;               j--;            }            else            {                i++;            }        }        if(stu[i].cardnum >= stu[left].cardnum)        {            i--;        }        p=stu[left];        stu[left]=stu[i];        stu[i]=p;        quicksort(stu,left,i);        quicksort(stu,j,right);    }}void sort(struct student stu[m]){    int i,j;    struct student p;    for(i=0;i<m;i++)    {        for(j=i+1;j<m;j++)        {            if(strcmp(stu[i].name,stu[j].name)>0)            {                p=stu[i];                stu[i]=stu[j];                stu[j]=p;            }        }    }}int twice_find(struct student stu[m],int key){    int low,high=m-1,mid;    while(low<=high)    {        mid=(low+high)/2;        if(stu[mid].cardnum == key) return mid;        if(stu[mid].cardnum>key)            high=mid-1;        else            low=mid+1;    }    return -1;}void display(struct student stu[m]){    int i;    printf("学生信息如下:\n");    printf("--------------------------\n");    for(i=0;i<m;i++)    {        printf("卡号:%ld\n姓名:%s\n院系:%s\n班级:%ld\n",stu[i].cardnum,stu[i].name,stu[i].academy,stu[i].class_num);        printf("--------------------------\n");    }}int main(){    struct student stu[m];    int i,key,j;    printf("请输入借书同学的信息:\n");    printf("--------------------------\n");    input(stu);    printf("请选择你想要的功能:\n");    printf("1.按照卡号进行排序。\n");    printf("2.按照姓名进行排序。\n");    printf("3.二分查找同学的信息。\n");    printf("4.退出系统。\n");    scanf("%d",&i);    switch(i)    {    case 1:        quicksort(stu,0,m-1);        printf("排序结果为:\n");        display(stu);        break;    case 2:        sort(stu);        printf("排序结果为:\n");        display(stu);        break;    case 3:        printf("请输入要查找的同学的卡号:");        scanf("%d",&key);        j=twice_find(stu,key);        printf("卡号:%ld\n姓名:%s\n院系:%s\n班级:%ld\n",stu[j].cardnum,stu[j].name,stu[j].academy,stu[j].class_num);        break;    case 4:        break;    }    return 0;}