Inventory Reorder Case - Modern Fortran Programming

A compact inventory case can scan in-memory tables and decide how many units to reorder.
Program

Play the program to choose an item id and compute the matching reorder quantity.
                            query_id
                            query_id = 103 (default)query_id = 101query_id = 102
                        

                            inventory_reorder_case.f90
                        
Replay: real traced execution (multi-file project)

                            program inventory_reorder_case_demo
    implicit none
    integer :: ids(3)
    integer :: stock(3)
    integer :: minimums(3)
    integer :: query_id
    integer :: i
    integer :: reorder

    ids = [101, 102, 103]
    stock = [5, 12, 2]
    minimums = [8, 10, 6]
    query_id = 103
    reorder = 0
    do i = 1, 3
        if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))
    end do
    print '(I0, 1X, I0)', query_id, reorder
end program inventory_reorder_case_demo
program inventory_reorder_case_demo
    implicit none
    integer :: ids(3)
    integer :: stock(3)
    integer :: minimums(3)
    integer :: query_id
    integer :: i
    integer :: reorder

    ids = [101, 102, 103]
    stock = [5, 12, 2]
    minimums = [8, 10, 6]
    query_id = 101
    reorder = 0
    do i = 1, 3
        if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))
    end do
    print '(I0, 1X, I0)', query_id, reorder
end program inventory_reorder_case_demo
program inventory_reorder_case_demo
    implicit none
    integer :: ids(3)
    integer :: stock(3)
    integer :: minimums(3)
    integer :: query_id
    integer :: i
    integer :: reorder

    ids = [101, 102, 103]
    stock = [5, 12, 2]
    minimums = [8, 10, 6]
    query_id = 102
    reorder = 0
    do i = 1, 3
        if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))
    end do
    print '(I0, 1X, I0)', query_id, reorder
end program inventory_reorder_case_demo

                        
1ids ← [101, 102, 103]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]⋯values this step[101, 102, 103]ids
2stock ← [5, 12, 2]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]12minimums = [8, 10, 6]⋯values this step[5, 12, 2]stock
3minimums ← [8, 10, 6]⋯11stock = [5, 12, 2]12minimums = [8, 10, 6]13query_id = 103⋯values this step[8, 10, 6]minimums
4query_id ← 103⋯12minimums = [8, 10, 6]13query_id = 10314reorder = 0⋯values this step103query_id
5reorder ← 0⋯13query_id = 10314reorder = 015do i = 1, 3⋯values this step0reorder
6i ← 1⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step1i
7if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(1) == query_id
8i ← 2⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step2i
9if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(2) == query_id
10i ← 3⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step3i
11reorder ← 4⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step4reorder.true.ids(3) == query_id
12print '(I0, 1X, I0)', query_id, reorder⋯17    end do18    print '(I0, 1X, I0)', query_id, reorder19end program inventory_reorder_case_demooutput103 4values this step103query_id4reorder
1ids ← [101, 102, 103]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]⋯values this step[101, 102, 103]ids
2stock ← [5, 12, 2]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]12minimums = [8, 10, 6]⋯values this step[5, 12, 2]stock
3minimums ← [8, 10, 6]⋯11stock = [5, 12, 2]12minimums = [8, 10, 6]13query_id = 101⋯values this step[8, 10, 6]minimums
4query_id ← 101⋯12minimums = [8, 10, 6]13query_id = 10114reorder = 0⋯values this step101query_id
5reorder ← 0⋯13query_id = 10114reorder = 015do i = 1, 3⋯values this step0reorder
6i ← 1⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step1i
7reorder ← 3⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step3reorder.true.ids(1) == query_id
8i ← 2⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step2i
9if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(2) == query_id
10i ← 3⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step3i
11if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(3) == query_id
12print '(I0, 1X, I0)', query_id, reorder⋯17    end do18    print '(I0, 1X, I0)', query_id, reorder19end program inventory_reorder_case_demooutput101 3values this step101query_id3reorder
1ids ← [101, 102, 103]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]⋯values this step[101, 102, 103]ids
2stock ← [5, 12, 2]⋯10ids = [101, 102, 103]11stock = [5, 12, 2]12minimums = [8, 10, 6]⋯values this step[5, 12, 2]stock
3minimums ← [8, 10, 6]⋯11stock = [5, 12, 2]12minimums = [8, 10, 6]13query_id = 102⋯values this step[8, 10, 6]minimums
4query_id ← 102⋯12minimums = [8, 10, 6]13query_id = 10214reorder = 0⋯values this step102query_id
5reorder ← 0⋯13query_id = 10214reorder = 015do i = 1, 3⋯values this step0reorder
6i ← 1⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step1i
7if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(1) == query_id
8i ← 2⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step2i
9reorder ← 0⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step0reorder.true.ids(2) == query_id
10i ← 3⋯14reorder = 015do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯values this step3i
11if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))⋯15do i = 1, 316    if (ids(i) == query_id) reorder = max(0, minimums(i) - stock(i))17end do⋯values this step.false.ids(3) == query_id
12print '(I0, 1X, I0)', query_id, reorder⋯17    end do18    print '(I0, 1X, I0)', query_id, reorder19end program inventory_reorder_case_demooutput102 0values this step102query_id0reorder
lookup table Parallel arrays hold item ids, current stock, and minimum stock.
bounded reorder `max(0, minimums(i) - stock(i))` prevents negative orders.
scan The loop checks each row and updates the result when the id matches.