编译语法没错误 输出不正确 哪位大神指点一下 谢谢

源程序：
#include<stdio.h>
#include<stdlib.h>

int main(void)

{
struct st
{
int age ;
char name[20] ;
float score ;

};

int b ;
scanf("%d",&b);

struct st *a[50];
int i = 0 ;

for(i ; i<b ;i++)
{
a[i] = (struct st *) malloc(sizeof(struct st));
printf("please input age : ");
scanf("%d",a[i]->age);
printf("please input name : ");
scanf("%s",a[i]->name);
printf("please input score : ");
scanf("%.1f",a[i]->score);   
printf("\n");
}

for(i = 0 ;i<b ;i++)
{
printf("%d %s %f\n",a[i]->age, a[i]->name, a[i]->score);
}

return 0 ;
}

输出如下：
3
please input age : 22
please input name : dgrg
please input score : 99

please input age : please input name : bddfb
please input score : 99

please input age : please input name : gbdfb
please input score : 66

11492368 dgrg 18305179148001886000000000.000000
11473936 bddfb 0.000000
11473936 gbdfb 0.000000

--------------------------------
Process exited after 19.25 seconds with return value 0
请按任意键继续. . .