1.
#include <iostream>

using namespace std;

struct st
{
    string sname;
    string sid;
    float cgpa;
    int marks[3]={};

};

void set_student(struct st student[],int size )
{

        student[0].sname="Ahmed Jalal";
        student[0].sid="123";
        student[0].cgpa=3.65;
        student[0].marks[0]=10;
        student[0].marks[1]=19;
        student[0].marks[2]=20;

        student[1].sname="Ahmed kamal";
        student[1].sid="124";
        student[1].cgpa=3.95;
        student[1].marks[0]=20;
        student[1].marks[1]=19;
        student[1].marks[2]=20;
}
void disp(struct st student[],int size)
{
    int i,j;
    for(i=0;i<size;i++)
    {
        cout<<"Student info:"<<i+1<<endl;
        cout<<"NAME:"<<student[i].sname<<endl;
        cout<<"ID:"<<student[i].sid<<endl;
        cout<<"CGPA:"<<student[i].cgpa<<endl;
        cout<<"MARKS OF 3Quizzes:"<<endl;
        for(j=0;j<3;j++)
        {
            cout<<student[i].marks[j]<<endl;
        }

    }

}

int main()
{
    st student[2];
    set_student(student,2);
    disp(student,2);
}

3.#include <iostream>

using namespace std;

struct st
{
    string sname;
    string sid;
    float cgpa;
    int marks[3]={};


};

void set_student(struct st student[],int size )
{

        student[0].sname="Ahmed Jalal";
        student[0].sid="123";
        student[0].cgpa=3.65;
        student[0].marks[0]=10;
        student[0].marks[1]=19;
        student[0].marks[2]=20;

        student[1].sname="Ahmed kamal";
        student[1].sid="126";
        student[1].cgpa=3.95;
        student[1].marks[0]=20;
        student[1].marks[1]=19;
        student[1].marks[2]=20;


        int best quiz[20]={};
        float average marks[16.33]={};

};

void best quiz(struct st student[],int size)

{
student[0].best quiz=20;

};
void average marks(struct st student[],int size)
{
student[2].average marks=16.33;
}