我想把信息输入到结构体变量当中去 ，然后按照学号由小到大输出出来，想先编一个样本出来但是遇到这个问题，
#include<stdio.h>
#include<math.h>
#include<malloc.h>
#include<string.h>
#define N 3
struct student
{ char number[20], name[20];
   int score[3];
};
void main()
{
    int i=0,j,k;
struct student exchange ;
        struct student *student;
    student=(struct student*)malloc(100*sizeof(struct student));
    struct student a[N]={
        {"27","赵滨",522},
        {"12","王子豪",522},
        {"3","尚晓琼",522}
            };
             for(k=i;k>0;k--)
                for(j=i;j>i-k;j--)
                {
                    if(strcmp(a[j].number,a[j-1].number)>0)
                    {strcpy(exchange.name,a[j].name);
                    strcpy(a[j].name,a[j-1].name);
                    strcpy(a[j-1].name,exchange.name);
                    exchange.number=a[j-1].number;
                    a[j-1].number=a[j].number;
                    a[j].number=exchange.number;D:\新建文件夹\Microsoft Visual Studio\MyProjects\学生情况表\情况表.cpp(28) : error C2106: '=' : left operand must be l-value
D:\新建文件夹\Microsoft Visual Studio\MyProjects\学生情况表\情况表.cpp(29) : error C2106: '=' : left operand must be l-value
D:\新建文件夹\Microsoft Visual Studio\MyProjects\学生情况表\情况表.cpp(30) : error C2106: '=' : left operand must be l-value