grade_report.jl in Julia

Report cards from a struct roster, guard-clause grading, and vcat.

# Average each student's scores and print a letter-grade report card.

using Printf

struct Student
    name::String
    scores::Vector{Int}
end

roster = [
    Student("Ada", [92, 88, 97]),
    Student("Grace", [84, 91, 78]),
    Student("Alan", [70, 66, 74]),
    Student("Edsger", [58, 67, 61]),
]

average(s::Student) = sum(s.scores) / length(s.scores)

function letter(avg)
    avg >= 90 && return 'A'
    avg >= 80 && return 'B'
    avg >= 70 && return 'C'
    avg >= 60 && return 'D'
    return 'F'
end

println("student  avg grade")
for s in sort(roster, by = s -> s.name)
    @printf("%-8s %4.1f  %c\n", s.name, average(s), letter(average(s)))
end

all_scores = reduce(vcat, [s.scores for s in roster])
@printf("Class average: %.1f\n", sum(all_scores) / length(all_scores))

How it works

1. Student holds a name and scores; average is one line.
2. letter returns through a ladder of && guards.
3. reduce(vcat, ...) pools every score for the class average.

Keywords and builtins used here

• Int
• String
• Student
• Vector
• end
• for
• function
• in
• return
• struct
• using

The run, in numbers

Lines

33

Characters to type

734

Tokens

213

Three-star pace

65 tpm

At the three-star pace of 65 tokens a minute, this run takes about 197 seconds.

Type this snippet

Step 2 of 3 in Encore, step 26 of 27 in Language basics.

← Previous Next →