Help with class roster using struct

[cfm310]

I really need help with the following program. I have done everything except for #3 and #4. I cant seem to figure out what to do for it exactly. Any answers, hints, or tips would be greatly appreciated.
Out: 4/22
Due: 5/1 by 11:50 PM
Learning Objectives
• To Use an Array of Structures in a Program
• To review modular programming and text file input and output,
• To review the desing of a text-based menu-driven program,
• To review call by reference,
• To use linear search and an array shift,
• To use an elementary sort algorithm on an array.
Problem Scenario: A basic class roster application is to be developed. The
application has the following functionalities:
1. ADD
Adds a new Student record if the assigned studentID has not been
already assigned to another student or displays a message indicating
that the student ID # has been already assigned,
2. DELETE
Deletes the student’s record whose ID # is entered or displays a message
indicating that the ID # has not been assigned,
3. EDIT
Edits a student’s record if the ID # is on the class roster or displays
a message indicating that the ID # has not been assigned (the first
name, middle initial and/or last name may be changed),
4. INQUIRY
displays the name of the student with the specified ID # or displays a
message indicating that the ID # has not been assigned, and
Duncan 1 Spring 2014Roster Application CSc 1253: Programming Project # 6
5. LISTING
Sorts by student ID # and generates the class row.
C L A S S R O S T E R
Student ID # First Name M.I. Last Name
---------------------------------------------
105-85-7251 Paul Z. Abramson
125-78-5241 Zachary Q. Bourgeois
410-78-3415 Emmanuel T. Woods
417-85-4554 Sarah H. Hallowanger
604-89-7142 Julia M. Morgan
902-54-7852 Jamesetta R. Hudson
---------------------------------------------
Enrollment: 6

code:
* edits a Student record given the specified student ID when
* the roster array contains the ID; display a message indicating
* that the student ID has not been assigned if studentID field is
* not in the roster array
* @param roster an array of student records
* @param numStuds the number of students (class size)
* @param sID the student's ID #
*/
void editStudent(Student roster[], int numStuds, string sID)
{

}

/**
* display a Student record given the specified student ID when
* the roster array contains the ID; display a message indicating
* that the student ID has not been assigned if studentID field is
* not in the roster array
* @param roster an array of student records
* @param numStuds the number of students (class size)
* @param sID the student's ID #
*/
void studentInquiry(const Student roster[], int numStuds, string sID)
{
/** 5. implement this function **/
}