c++新手求大神找一下错误

#include<iostream>
#include<string>
using namespace std;
struct gread
{
int num=3;
float math;
float english;
float c++;
};
int main()
{
gread[3]={{{0,0,1},60,70,80},{{0,0,2},70,80,90},{{0,0,3},20,30,15}};
cout<<"学生成绩名单\n";
cout<<"学号\t高数\t英语\tc++\t平均分\t";
for(int i=0;i<=2;i++){
for(int j=0;j<=2;j++){
cout<<gread[i].num[j];
}
cout<<gread[i].math<<"/t"<<gread[i].english<<"/t"<<gread[i].c++<<"/t"<<(gread[i].math+gread[i].english+<gread[i].c++)/3<<engl;
}
return 0;
}