Program to understand how an array of structures is sent to a function

#include<stdio.h>
struct student
{
char name[20];
int rollno;
int marks;
};
void display(struct student);
void dec_marks(struct student stuarr[ ]);
main( )
{
int i;
struct student stuarr[3] =
{
{"Mary", 12, 98},
{"John", 11, 97},
{"Tom", 12, 89}
};
dec_marks(stuarr);
for(i=0; i<3; i++ )
display(stuarr[i]);
}
void dec_marks(struct student stuarr[])
{
int i;
for(i=0; i<3; i++)
stuarr[i].marks = stuarr[i].marks-10;
}
void display(struct student stu)
{
printf("Name  - %s\t", stu.name);
printf("Rollno  - %d\t", stu.rollno);
printf("Marks  - %d\n", stu.marks);
}