c语言问题

#include <stdio.h>

struct student

{

char name[20];

int score;

}grade[5];

main()

{

int i,avg,sum,b=0,t;

printf("input name and score\n");

for(i=0;i++;i<5)

scanf("%s%d",grade[i].name,&grade[i].score);

for(i=0;i++;i<5)

sum=sum+grade[i].score;

avg=sum/5;

for(i=0;i++;i<5)

{

if(grade[i].score<60)

{

b++;

printf("%s",grade[i].name);

}

}

printf("sum=%d\n",sum);

printf("avg=%d\n",avg);

printf("the number under 60 is=%d\n",b);

}

为什么我执行的时候,没发输入.一按键盘就退出.下次在执行时显示:

"input name and score

sum=2490

avg=498

then nuber under 60 is =0"

怎么会这样,各位帮帮我,我是刚学的,麻烦解释的明白点,多谢

for(i=0;i++;i<5) ===> for(i=0;i<5;i++)