Average Grade

Part of the Logic & Flow section of Coddy's GDScript journey. Lesson 46 of 78.

Challenge

Easy

Calculate the average grade of a student. Keep everything you wrote in the previous steps.

1. The function. Below the other functions, write calculate_average_grade(student_name: String) -> float:

If student_records does not have the name, print Student '<name>' not found. and return -1.0. No real average is negative, so the caller can tell that the student was missing.
If the student has no grades yet, return 0.0.
Otherwise return the sum of the grades divided by how many there are, as a float.

2. The command. Add this branch for average <name> above ["show"]. It prints the average with two decimals, unless the student was not found:

["average", var student]:
	var average := calculate_average_grade(student)
	if average >= 0:
		print("Average grade of '%s': %.2f" % [student, average])

For the commands

add Alice 20 Math Physics
add Bob 22 Biology Chemistry
grade Alice 90
grade Alice 85
grade Bob 75
average Alice
average Bob
average Charlie
exit

the output is:

Student 'Alice' added successfully.
Student 'Bob' added successfully.
Grade 90 added for student 'Alice'.
Grade 85 added for student 'Alice'.
Grade 75 added for student 'Bob'.
Average grade of 'Alice': 87.50
Average grade of 'Bob': 75.00
Student 'Charlie' not found.
Goodbye!

Try it yourself

extends Node

# Every student: name -> {"age": int, "grades": Array, "courses": a set of course names}
var student_records := {}

func _ready():
	while true:
		var parts := Array(OS.read_string_from_stdin().split(" ", false))
		match parts:
			["add", var student, var age, ..]:
				add_student(student, int(age), parts.slice(3))
			["grade", var student, var grade]:
				add_grade(student, int(grade))
			["enrolled", var student, var course]:
				print(is_enrolled(student, course))
			["show"]:
				print(student_records)
			["exit"]:
				print("Goodbye!")
				break

func add_student(student_name: String, age: int, courses: Array) -> void:
	if student_records.has(student_name):
		print("Student '%s' already exists." % student_name)
		return
	var course_set := {}
	for course in courses:
		course_set[course] = true
	student_records[student_name] = {"age": age, "grades": [], "courses": course_set}
	print("Student '%s' added successfully." % student_name)

func add_grade(student_name: String, grade: int) -> void:
	if not student_records.has(student_name):
		print("Student '%s' not found." % student_name)
		return
	student_records[student_name]["grades"].append(grade)
	print("Grade %d added for student '%s'." % [grade, student_name])

func is_enrolled(student_name: String, course: String) -> bool:
	if not student_records.has(student_name):
		print("Student '%s' not found." % student_name)
		return false
	return student_records[student_name]["courses"].has(course)