Need Help with my program

[Cesar23]

When i print out the info the user inputs it gives me garbage.
when i print out the name it comes out blank and the grades are bunch of random numbers as well as the average.
Maybe I'm calling the functions wrong.


#include<iostream>
#include<string>
using namespace std;

//Abstract data type
struct Student
{
string name;
int id;
double grades[4];
};

//Prototype
void studentInfo(Student);
double getAverage(Student &);
void printInfo(Student, double);

int main()
{

//Declare variables
Student person;
double average;
Student* personPtr = &person;
//Program introduction
cout << "Hello. This program is design for you to input student information" << endl;
cout << "You will have to enter the student name, id and four test grades." << endl;
cout << "It will drop the lowest grade and give you th average of the remaining grades" << endl;
cout << "At the end of the program it will display all the information you inputed." << endl;
cout << "Lets begin." << endl;
//Calling functions
studentInfo(person);
cout << "------------------------------------" << endl;
average = getAverage(person);
printInfo(*personPtr, average);
cout << "------------------------------------" << endl;

//--------------------------
system("pause");
return 0;
}

//Aquires the student infomation
void studentInfo(Student person)
{
cout << "Enter the students name:";
getline(cin, person.name);
cout << "Enter " << person.name << " ID number:";
cin >> person.id;
cin.ignore();
for (int i = 0; i < 4; i++)
{
cout << "Enter a grade for test #" << i + 1 << ": ";
cin >> person.grades[i];
}
}

//Gets the average of the top 3 grades
double getAverage(Student &person)
{
double average;
double lowestGrade = person.grades[0];
for (int i = 0; i < 4; i++)
{
if (lowestGrade > person.grades[i])
lowestGrade = person.grades[i];
}
average = ((person.grades[0] + person.grades[1] + person.grades[2] + person.grades[3]) - lowestGrade) / 3;
return average;
}

//Print all the info aquired
void printInfo(Student person, double average)
{
cout << "Name.............................................. " << person.name << endl;
cout << "ID number......................................... " << person.id << endl;
for (int i = 0; i < 4; i++)
{
cout << "Test grade #" << i + 1 << "....................................... " << person.grades << endl;
}
cout << "Average of the three highest grades............... " << average << endl;
}

[ne555]

http://www.cplusplus.com/doc/tutorial/functions/ (see «Arguments passed by value and by reference»)
studentInfo(person); is useless, it has no effect.

[Cesar23]

So then how do i call it?
I tried renaming it on the function, but it still doesn't print it out.

[AbstractionAnon]

To expand on ne555's response,

void studentInfo(Student person)

You're passing person by value. Any changes made by that function are lost when that function exits because you're operating on a local copy of it. Not the caller's instance of it. You want to pass person by reference here so that the caller's instance of the struct is updated.

void studentInfo(Student & person)